[Federal Register Volume 85, Number 194 (Tuesday, October 6, 2020)]
[Rules and Regulations]
[Pages 62981-62990]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 2020-21996]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. FAA-2016-6145; Product Identifier 2015-NM-056-AD; Amendment 
39-21223; AD 2020-18-02]
RIN 2120-AA64


Airworthiness Directives; The Boeing Company Airplanes

AGENCY: Federal Aviation Administration (FAA), DOT.

ACTION: Final rule.

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SUMMARY: The FAA is adopting a new airworthiness directive (AD) for 
certain The Boeing Company Model 747-400, 747-400D, and 747-400F series 
airplanes. This AD was prompted by the FAA's analysis of the Model 747 
fuel system reviews conducted by the manufacturer. This AD requires

[[Page 62982]]

modifying the fuel quantity indicating system (FQIS) to prevent 
development of an ignition source inside the center fuel tank due to 
electrical fault conditions. This AD also provides alternative actions 
for cargo airplanes. The FAA is issuing this AD to address the unsafe 
condition on these products.

DATES: This AD is effective November 10, 2020.
    The Director of the Federal Register approved the incorporation by 
reference of certain publications listed in this AD as of November 10, 
2020.

ADDRESSES: For service information identified in this final rule, 
contact Boeing Commercial Airplanes, Attention: Contractual & Data 
Services (C&DS), 2600 Westminster Blvd., MC 110-SK57, Seal Beach, CA 
90740-5600; telephone 562-797-1717; internet https://www.myboeingfleet.com. You may view this service information at the 
FAA, Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability of 
this material at the FAA, call 206-231-3195. It is also available on 
the internet at https://www.regulations.gov by searching for and 
locating Docket No. FAA-2016-6145.

Examining the AD Docket

    You may examine the AD docket on the internet at https://www.regulations.gov by searching for and locating Docket No. FAA-2016-
6145; or in person at Docket Operations between 9 a.m. and 5 p.m., 
Monday through Friday, except Federal holidays. The AD docket contains 
this final rule, any comments received, and other information. The 
address for Docket Operations is U.S. Department of Transportation, 
Docket Operations, M-30, West Building Ground Floor, Room W12-140, 1200 
New Jersey Avenue SE, Washington, DC 20590.

FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer, 
Propulsion Section, FAA, Seattle ACO Branch, 2200 South 216th St., Des 
Moines, WA 98198; phone and fax: 206-231-3557; email: 
[email protected].

SUPPLEMENTARY INFORMATION:

Discussion

    The FAA issued a notice of proposed rulemaking (NPRM) to amend 14 
CFR part 39 by adding an AD that would apply to certain The Boeing 
Company Model 747-400, 747-400D, and 747-400F series airplanes. The 
NPRM published in the Federal Register on May 3, 2016 (81 FR 26490). 
The NPRM was prompted by the FAA's analysis of the Model 747 fuel 
system reviews conducted by the manufacturer. The NPRM proposed to 
require modifying the FQIS to prevent development of an ignition source 
inside the center fuel tank due to electrical fault conditions. The 
proposed AD also proposed to provide alternative actions for cargo 
airplanes.
    The FAA is issuing this AD to address ignition sources inside the 
center fuel tank, which, in combination with flammable fuel vapors, 
could result in a fuel tank explosion and consequent loss of the 
airplane.

Comments

    The FAA gave the public the opportunity to participate in 
developing this final rule. The following presents the comments 
received on the NPRM and the FAA's response to each comment.

Support for the NPRM

    The Air Line Pilots Association, International (ALPA) and National 
Air Traffic Controllers Association (NATCA) supported the intent of the 
NPRM. Additional comments from NATCA are addressed below.

Request To Withdraw NPRM: Unjustified by Risk

    Airlines for America and the Cargo Airline Association, in 
consolidated comments (A4A/CAA), United Parcel Service (UPS) and KLM 
Royal Dutch Airlines (KLM) requested that the FAA withdraw the NPRM. 
A4A/CAA and UPS cited comments submitted by Boeing to Docket No. FAA-
2012-0187 in which Boeing stated that the risk is ``less than extremely 
improbable.'' A4A/CAA added that Boeing does not believe that an unsafe 
condition exists. UPS stated the Boeing's comments demonstrate an 
unsafe condition does not exist. A4A/CAA and UPS noted that they 
consider the Boeing comments to be applicable to the airplane models in 
the NPRM. KLM added that it understands that Boeing is not able to 
explain or substantiate the rationale behind the NPRM.
    KLM and Martinair stated that the NPRM does not clarify the 
necessity of additional actions beyond the currently mandated Special 
Federal Aviation Regulation (SFAR) No. 88 (in 14 CFR part 21), related 
service bulletins, airworthiness limitations, and critical design 
configuration control limitations. UPS stated that an agency is 
required to consider all relevant factors and articulate a satisfactory 
explanation for its action. UPS noted that the FAA is apparently basing 
its decision to issue the AD on historical SFAR 88 design reviews that 
have been superseded by the more recent Boeing analysis and favorable 
operational experience in the years since the SFAR 88 reviews were 
completed.
    The FAA disagrees with the commenters' request. The FAA notes that 
Boeing's comments were addressed in the supplemental NPRM (SNPRM) for 
Docket No. FAA-2012-0187 (80 FR 9400, February 23, 2015) in the comment 
response for ``Request To Withdraw NPRM (77 FR 12506, March 1, 2012): 
Unjustified by Risk.'' As explained in that comment response, in 
addition to examining average risk and total fleet risk, the FAA 
examines the individual flight risk on the worst reasonably anticipated 
flights. In general, the FAA issues ADs in cases where reasonably 
anticipated flights with preexisting failures (either due to latent 
failure conditions or allowable dispatch configurations) are vulnerable 
to a catastrophic event due to an additional foreseeable single failure 
condition. This is because the FAA considers operation of flights 
vulnerable to a potentially catastrophic single failure condition to be 
an excessive safety risk to the passengers on those flights. The FAA 
has determined that the currently mandated SFAR 88 service bulletins, 
airworthiness limitations, and critical design configuration control 
limitations do not adequately address the unsafe condition identified 
in this AD and therefore it is necessary to issue this final rule. The 
FAA has not changed this AD regarding this issue.

Request To Withdraw NPRM: No Unsafe Condition

    Boeing requested that the FAA withdraw the NPRM. Boeing suggested 
that, by requiring center fuel tank FQIS wire separation for passenger 
airplanes that have not incorporated a nitrogen generating system 
(NGS), the NPRM specifically addresses airplanes regulated by the 
European Union Aviation Safety Agency (EASA) and other civil aviation 
authorities and the lack of a flammability reduction means (FRM) rule. 
Boeing stated that because it considered the use of FRM (NGS) to 
address unknown ignition sources as the final corrective action, Boeing 
has not developed center tank FQIS wire separation service instructions 
for passenger aircraft. Boeing stated that it believes no unsafe 
condition exists and does not feel that the lack of FRM rule 
harmonization should cause additional work and expense for airlines.
    The FAA disagrees with the commenter's request. The FAA determined 
that an unsafe condition exists using the criteria in FAA Policy 
Memorandum ANM100-2003-112-15,

[[Page 62983]]

``SFAR 88--Mandatory Action Decision Criteria,'' dated February 25, 
2003.\1\ That policy was used to evaluate the noncompliant design areas 
identified in the manufacturer's fuel system reviews and to determine 
which noncompliance issues were unsafe conditions that required 
corrective action under 14 CFR part 39. The FAA's unsafe condition 
determination was not based on an assessment of average risk or total 
fleet risk, but rather was driven by the qualitative identification of 
an unacceptable level of individual risk that exists on flights that 
are anticipated to occur with a preexisting latent in-tank failure 
condition and with a flammable center fuel tank. For these reasons, and 
based on further detailed responses to similar comments in the SNPRM 
for Docket No. FAA-2012-0187, and in the subsequently issued final 
rule, AD 2016-07-07, Amendment 39-18452 (81 FR 19472, April 5, 2016) 
(``AD 2016-07-07''), which addressed the same unsafe condition for 
Boeing Model 757 airplanes, the FAA has determined that it is necessary 
to issue this final rule.
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    \1\ https://rgl.faa.gov/Regulatory_and_Guidance_Library/
rgPolicy.nsf/0/dc94c3a46396950386256d5e006aed11/$FILE/Feb2503.pdf.
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Request To Withdraw NPRM: Probability Analysis Inconsistent With 
Regulatory Requirements

    A4A/CAA and UPS requested that the FAA withdraw the NPRM. The 
commenters stated that the assumption of a single failure regardless of 
probability is inconsistent with 14 CFR part 25 regulatory 
requirements. The commenters referred to the phrase ``regardless of 
probability'' associated with single failures. A4A/CAA and UPS 
acknowledged that the term is used with single failures in FAA Advisory 
Circular (AC) 25.981-1C,\2\ ``Fuel Tank Ignition Source Prevention 
Guidelines,'' but since that term does not appear in 14 CFR 
25.981(a)(3), the commenters considered its use arbitrary, possibly 
introducing additional requirements not included in that section. A4A/
CAA and UPS stated that the ``worst reasonably anticipated flight'' is 
a flight with a latent FQIS failure and a high-flammability tank, and 
this ``latent plus one'' failure--regardless of probability of a single 
failure--is not consistent with 14 CFR 25.981(a)(3).
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    \2\ https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_25.981-1C.pdf.
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    The FAA disagrees with the commenters' request. The FAA notes that 
the commenters' assertion about the intent of 14 CFR 25.981(a)(3) is 
incorrect based on both the language of the rule and on the published 
rulemaking documents. The absence of a probabilistic qualifier in both 
the ``from each single failure'' clause and in the ``from each single 
failure in combination with each latent failure not shown to be 
extremely remote'' clause in 14 CFR 25.981(a)(3) in fact means just 
that--there is no probabilistic qualifier intended by the regulation. 
The intent for single failures in these two scenarios to be considered 
regardless of probability of the single failure was explicitly stated 
in the NPRM for 14 CFR 25.981, as amended by amendment 25-102 (66 FR 
23085, May 7, 2001) (``amendment 25-102''). That NPRM stated, in 
pertinent part, that it would also add a new paragraph (a)(3) to 
require that a safety analysis be performed to demonstrate that the 
presence of an ignition source in the fuel tank system could not result 
from ``any single failure, from any single failure in combination with 
any latent failure condition not shown to be extremely remote, or from 
any combination of failures not shown to be extremely improbable.'' 
These new requirements would define three scenarios that must be 
addressed in order to show compliance with the proposed paragraph 
(a)(3). ``The first scenario is that any single failure, regardless of 
the probability of occurrence of the failure, must not cause an 
ignition source. The second scenario is that any single failure, 
regardless of the probability occurrence, in combination with any 
latent failure condition not shown to be at least extremely remote 
(i.e., not shown to be extremely remote or extremely improbable), must 
not cause an ignition source. The third scenario is that any 
combination of failures not shown to be extremely improbable must not 
cause an ignition source.''
    The preamble to the final rule for amendment 25-102 made a nearly 
identical statement, including the same uses of the phrase ``regardless 
of probability.'' The FAA has determined that it is necessary to 
proceed with issuance of this final rule as proposed. Further details 
and a description of the FAA's risk assessment can be found in 
responses to similar comments in a related SNPRM that addressed the 
same unsafe condition for Model 757 airplanes, in Docket No. FAA-2012-
0187, and in the subsequently issued final rule, AD 2016-07-07, 
amendment 39-18452 (81 FR 19472, April 5, 2016) (``AD 2016-07-07''). No 
change to this AD was made in response to these comments.

Request To Withdraw NPRM: No New Data Since Fuel Tank Flammability 
Reduction (FTFR) Rulemaking

    A4A/CAA and UPS requested that the FAA withdraw the NPRM based on a 
lack of new data since the issuance of the FTFR rule (73 FR 42444, July 
21, 2008). The commenters referred to the FTFR rule and decision to not 
require FRM for all-cargo airplanes, and the FAA's intent to gather 
additional data and consideration of further rulemaking if flammability 
of these airplanes is excessive. UPS stated that since the FTFR rule, 
no additional data has been publicly introduced that would support or 
justify the applicability of this rulemaking to all-cargo aircraft. The 
commenters also referred to the FAA's response to comments in the 
preamble to the SNPRM for Docket No. FAA-2012-0187, which documented 
the FAA's decision on applicability of FRM and cost estimates. The 
commenters stated that the FAA response was misleading and not factual 
since manufacturers did not begin detailed designs to address the 
proposed unsafe condition until after the FTFR rule was published. The 
commenters added that the FAA did not discuss other changes to the FQIS 
system in the FTFR rule.
    The FAA disagrees with the commenters' request. The FAA notes that 
the FTFR rule and FQIS ADs are two different issues with separate FAA 
actions. The intent of the FTFR rule was to provide an order of 
magnitude reduction in the rate of fuel tank explosions for the 
airplanes affected by that rule through adding a new airworthiness 
standard for the flammability of fuel tanks. The FAA notes that the 
FTFR rule was never intended to be a replacement for the issuance of 
ADs to address identified unsafe conditions. An unsafe condition due to 
the identified FQIS latent-plus-single failure issue in high-
flammability fuel tanks was determined to exist during the SFAR 88 AD 
Board held by the FAA in 2003 using the guidance in FAA Policy 
Memorandum ANM100-2003-112-15 for high-flammability fuel tanks, 
including the center fuel tank on Model 747-400 airplanes. That same 
issue was not considered to be an unsafe condition in low-flammability 
wing fuel tanks based on that same policy memorandum. The FAA has not 
changed this AD regarding this issue.

Request To Withdraw NPRM: Arbitrary and Inconsistent Wire Separation 
Standards

    A4A/CAA and UPS requested that the FAA withdraw the NPRM based on a 
lack of consistent design standards for

[[Page 62984]]

FQIS wire separation. The commenters assumed that the approved standard 
for the retrofit is a 2-inch wire separation minimum, which the 
commenters considered arbitrary and inconsistently applied. The 
commenters reported that the amount of wiring capable of meeting that 
separation standard varies widely among airplane models. A4A/CAA and 
UPS also acknowledged that other separation methods were used in areas 
not meeting the 2-inch wire separation requirement.
    The FAA does not agree with the commenters' request. The degree of 
physical isolation of FQIS wiring from other wiring, whether provided 
by physical distance or barrier methods, that is necessary to eliminate 
the potential for hot shorts due to wiring faults is dependent on the 
materials used, the wire securing methods, and the possible types of 
wiring faults. The FAA relied on the manufacturer to assess the details 
of the design and to propose the appropriate isolation measures. While 
2 inches of physical separation may appear to be an arbitrary number, 
it was the distance proposed by the manufacturer as appropriate for 
their design based on analysis of the design details. The FAA has not 
changed this AD regarding this issue.

Request To Withdraw NPRM: NPRM Arbitrary and Inconsistently Applied

    A4A/CAA and UPS requested that the FAA withdraw the NPRM. The 
commenters noted that airplanes with FRM are not included in the 
applicability, and the NPRM would therefore not fully address the 
unsafe condition. The commenters added that the distinction between 
high- and low-flammability exposure time fuel tanks as used in the NPRM 
is arbitrary. The commenters stated that an arbitrary differentiation 
of high- versus low-flammability as decisional criteria for the need 
for corrective action does not take into account the actual probability 
of the impact of the difference in flammability on the potential of 
catastrophic failure. The commenters also stated that allowing the 
proposed alternative actions for cargo airplanes does not fully address 
the unsafe condition in the NPRM. The commenters referenced the FAA's 
response to comments in AD 2016-07-07 regarding this issue. The 
commenters summarized numerical analysis showing no significant 
difference in risk between high- and low-flammability fuel tanks. The 
commenters concluded that the FAA's risk analysis is arbitrary and an 
unsafe condition does not exist.
    The FAA disagrees with the assertion that the NPRM is arbitrary and 
inconsistent. The NPRM follows defined policy in FAA Policy Memorandum 
ANM100-2003-112-15, and consistently applies the policy to several 
airplane models with similar unsafe conditions, similar to AD 2016-07-
07. The FAA defined the difference between low- and high-flammability 
exposure time fuel tanks based on recommendations from the Aviation 
Rulemaking Advisory Committee Fuel Tank Harmonization Working Group 
(FTHWG). The preamble to the final rule for amendment 25-102, which 
amended 14 CFR 25.981, defined this difference as based upon comparison 
of ``the safety record of center wing fuel tanks that, in certain 
airplanes, are heated by equipment located under the tank, and unheated 
fuel tanks located in the wing.'' The FTHWG concluded that the safety 
record of fuel tanks located in the wings was adequate and that if the 
same level could be achieved in center wing fuel tanks, the overall 
safety objective would be achieved.
    In the response to comments in the preamble to the final rule for 
AD 2016-07-07 referenced by the commenters, the FAA described why FRM 
or alternative actions for cargo airplanes provide an acceptable level 
of safety, even if they do not completely eliminate the non-compliance 
with 14 CFR 25.981(a)(3).
    The fuel tank explosion history for turbojet/turbofan powered 
transport airplanes fueled with kerosene type fuels, outside of 
maintenance activity, has consisted of explosions of tanks that (1) are 
not conventional aluminum wing tanks and (2) spend a considerable 
amount of their operating time empty. The service history of 
conventional aluminum wing tanks has been acceptable. The intent of the 
difference in decision criteria in FAA Policy Memorandum ANM100-2003-
112-15 was to give credit for this satisfactory service experience, and 
to differentiate between tanks with a level of flammability similar to 
that of a conventional wing tank and those with a significantly higher 
level of flammability.
    The numerical analysis provided by the commenters is inconsistent 
with the fuel tank explosion service history. There are at least three 
identifiable physics-based reasons for that inconsistency. First, low-
flammability tanks on most types of airplanes are main tanks that are 
the last tanks used. During a large portion of their operating time, 
the systems and structural features that have the potential to be 
ignition sources in the event of a failure condition are covered with 
liquid fuel, and an ignition source, if it occurs, is likely to be 
submerged. When a potential ignition source in a main tank is 
uncovered, it is likely to be later in the flight when the tank is cool 
and no longer flammable. The commenters' analysis does not account for 
this significant effect. Second, the numerical analysis used by the 
commenters assumes that any given ignition source has a random 
occurrence in time at the estimated probability, and that, in order for 
an explosion to occur, that random occurrence of an ignition source 
needs to coincide with the tank being in a flammable state. In fact, 
many of the identified ignition threats do not simply occur briefly and 
then go away. Instead, a fault occurs that, until it is discovered and 
corrected, repeatedly creates an ignition source, and repeatedly tests 
whether flammable conditions exist.
    Third, the flammability of low-flammability fuel tanks is typically 
dependent on weather, and a low-flammability fuel tank may operate for 
months without ever becoming flammable. This is not true of most high-
flammability fuel tanks, which typically have significant on-airplane 
heat sources driving their temperature. This factor can mean that, on 
some airplanes, an in-tank latent failure can occur and, after some 
period of time, be detected and corrected without the low-flammability 
tank ever having flammable conditions. The numerical analysis provided 
by the commenters does not account for these significant factors. The 
difference in likelihood of a failure that results in repeated ignition 
source events causing a tank explosion is not simply proportional to 
difference in the fleet average flammability of the tank for the 
reasons stated above. The FAA has not changed this AD regarding this 
issue.

Request To Withdraw NPRM: Inadequate Fleet Exposure and Cost Estimates

    Boeing requested that the FAA withdraw the NPRM. Boeing stated that 
the fleet exposure for the affected fleet continues to decrease due to 
aging airplanes and production stopping on Model 747-400 airplanes. 
Boeing added that the estimated costs in the NPRM do not take into 
account the costs of compliance for passenger airplanes without FRM 
installed.
    The FAA disagrees with the commenter's request. The FAA did not 
base its unsafe condition determination on fleet risk but instead on 
individual risk. This is discussed in detail in the response to 
comments in the SNPRM for Docket No. FAA-2012-0187, under the heading 
``Request To Withdraw NPRM (77 FR 12506, March 1, 2012):

[[Page 62985]]

Unjustified by Risk.'' Therefore, the age of the airplane and its 
current production stoppage do not affect the determination that an 
unsafe condition still exists on an individual airplane.
    The NPRM for this proposed rule did contain a cost estimate for 
passenger airplanes that was based on the estimate provided by Boeing 
for the Model 757 and Model 767 airplanes, which have an FQIS of 
similar design. The FAA notes that Boeing asserted that the cost to 
operators of modifying an airplane's FQIS to be fully compliant with 
the airworthiness standards would be similar to the cost of installing 
Boeing's NGS flammability reduction system. Based on that, Boeing 
requested that the FAA agree to not require Boeing to develop service 
information for a fully compliant FQIS modification. However, the FAA 
used Boeing's estimate of the cost to modify the Model 757 and Model 
767 FQIS to a fully part-25-compliant configuration to provide the 
estimated costs in the NPRM, based on an assumption that the cost for 
Model 747 airplanes would be similar. At the time, Boeing concurred 
with this estimate. This is discussed in detail in the response to 
comments in the SNPRM for Docket No. FAA-2012-0187. Therefore, the FAA 
has not changed this AD regarding this issue.

Request To Withdraw NPRM: Insufficient Justification for AD

    Based on an assertion that the FAA did not sufficiently explain how 
the unsafe condition justifies AD rulemaking, UPS requested that the 
FAA withdraw the NPRM. UPS stated that the FTFR rule did not suggest 
that any future modifications of FQIS systems had been considered. UPS 
contended that all-cargo operators were surprised and prejudiced by 
costly proposed FQIS modifications that are unsupported by both an 
updated risk assessment and full cost/benefit analysis that consider 
the pertinent facts. UPS alleged that the FAA did not fully explain or 
justify its decision making for the NPRM, and concluded that the NPRM 
is arbitrary and does not reflect properly reasoned agency action.
    The FAA disagrees with the commenter's request. A review of the 
rulemaking record shows that the commenter's first assertion is not 
correct. The FAA notes that Section III.K.5. of the preamble of the 
FTFR rule states that ``the findings from the analysis required by SFAR 
88 showed that most transport category airplanes with high-flammability 
fuel tanks needed transient suppression units (TSUs) to prevent 
electrical energy from airplane wiring from entering the fuel tanks in 
the event of a latent failure in combination with a single failure.'' 
In addition, the NPRM for the FTFR rule (70 FR 70922, November 23, 
2005) states: ``As part of the safety reviews of SFAR 88, we have 
identified other models that likewise would need a transient 
suppression device.'' These statements indicate that the FAA expects to 
take AD action on multiple airplane models to address FQIS issues 
identified through the SFAR 88 analyses. The preamble of the FTFR rule 
also states that the proposed FRM has the potential to reduce the 
industry cost associated with those expected ADs because the 
installation of an FRM likely would eliminate the need to further 
address the FQIS issue through AD actions.
    The purpose of those statements was to note that there would be 
some cost savings to industry resulting from the elimination of other 
actions required to address an unsafe condition for the airplanes 
affected by the proposed rules, and to point out that the FAA did not 
take credit for those potential cost reductions in assessing the cost 
of the FTFR rule because the costs were not well understood at the 
time. That statement was not a commitment by the FAA to forego issuing 
ADs if necessary to address an identified unsafe condition on the 
airplanes but rather to not require the affected airplanes to 
incorporate FRM. As noted previously, the NPRM for the FTFR rule and 
the FTFR rule both made statements indicating that the FAA expects to 
issue AD actions on multiple airplane models to address FQIS issues 
identified through the SFAR 88 analyses. The FAA explained the unsafe 
condition and the risk on anticipated flights with a pre-existing 
latent failure condition in the NPRM to this final rule. The FAA also 
provided an estimate of the costs associated with the proposed AD in 
accordance with FAA rulemaking policy and the Administrative Procedures 
Act. The FAA has not changed this AD regarding this issue.

Request To Require Cargo Airplane Option for All Airplanes

    Boeing requested that the NPRM be revised to make the alternative 
actions for cargo airplanes specified in paragraph (h) of the proposed 
AD applicable to all airplanes, including passenger airplanes with FRM 
not installed due to differences in foreign regulations. In addition, 
Boeing requested that the actions specified in paragraph (h) of the 
proposed AD become the primary means of compliance for all airplanes, 
not an alternative method of compliance for some airplanes. In 
addition, KLM proposed that the FAA review if the ``Alternative Actions 
for Cargo Airplanes'' as described in paragraph (h) of the proposed AD 
is a possible acceptable means of compliance for passenger airplanes.
    The FAA disagrees with the commenters' requests. As discussed in 
the comment response in the SNPRM for Docket No. FAA-2012-0187, under 
the heading ``Requests To Withdraw NPRM (77 FR 12506, March 1, 2012) 
Based on Applicability'' the FAA does not consider the alternative 
action for cargo airplanes allowed by this AD to provide an adequate 
level of safety for passenger airplanes. The FAA is willing to accept a 
higher level of individual flight risk exposure for cargo flights that 
are not fail-safe due to the absence of passengers and the resulting 
significant reduction in occupant exposure on a cargo airplane versus a 
passenger airplane, and due to relatively low estimated individual 
flight risk that would exist on a cargo airplane after the corrective 
actions are taken. The FAA has not changed this AD regarding this 
issue.

Request To Record Only Certain Codes

    Boeing requested that paragraph (h)(1) of the proposed AD be 
revised to only require corrective actions if a nondispatchable fault 
code pertaining to the center wing tank is recorded (as opposed to any 
nondispatchable fault code being recorded). Boeing stated that all FQIS 
wire separation changes in the proposed AD are limited to the center 
wing tank, therefore only built-in test equipment (BITE) check messages 
pertaining to the center wing tank are applicable to the proposed AD.
    The FAA agrees that the unsafe condition addressed by this AD is 
limited to the center wing tank. However, the FAA does not agree that 
the AD should be changed as proposed by Boeing. It is not clear to the 
FAA whether there may be FQIS BITE fault codes that are not clearly 
identified as related to the center wing tank but that may impact 
center tank circuits. Therefore, the FAA has determined that all 
nondispatchable fault codes recorded prior to the BITE check or as a 
result of the BITE check required by paragraph (h)(1) of this AD must 
be addressed. Operators or Boeing may request an alternative method of 
compliance (AMOC) under the provisions of paragraph (i) of this AD if 
they can provide sufficient data that a particular fault code does not 
pertain to the unsafe condition addressed by this AD.
    Regarding the requirement to record and address fault codes read

[[Page 62986]]

immediately prior to running the BITE check procedure, the FAA notes 
that the normal Boeing procedure for performing an FQIS BITE check is 
to first erase all of the existing fault codes, then perform the BITE 
check and troubleshoot any resulting new fault codes. For this AD, the 
FAA did not want any already stored fault codes to be potentially 
ignored due to erasure at the first step because some of the failures 
of concern can be intermittent. This AD therefore requires operators to 
record the existing codes before doing the BITE check, then do the BITE 
check and record the new codes that result from that BITE check, and 
then do the appropriate troubleshooting and corrective action for both 
sets of codes per the manufacturer's guidance. The FAA has not changed 
this AD regarding this issue.

Request To Exclude Certain Airplanes

    Delta Airlines (DAL) requested that the FAA revise the proposed AD 
to exclude airplanes that are affected by 14 CFR 121.1117. DAL and 
United Airlines (UAL) noted that the FRM required by 14 CFR 121.1117 
will have been installed on all affected airplanes in passenger 
configuration by December 26, 2018. DAL suggested modifying paragraph 
(c) of the proposed AD to clarify that the proposed AD is only 
applicable to aircraft that are not affected by 14 CFR 121.1117. UAL 
also suggested that the FAA either delete paragraph (g) of the proposed 
AD or make paragraph (g) of the proposed AD applicable only to 
airplanes in a cargo configuration that do not have an FRM installed 
and non-U.S.-registered airplanes that do not have to comply with FRM 
requirements.
    The FAA disagrees with the commenters' requests. There are other 
passenger-carrying airplanes operated under 14 CFR part 91 that are not 
required to install FRM. (The requirement to install FRM on all 
passenger-carrying airplanes operated by air carriers is in 14 CFR 
121.1117.) The FAA notes that foreign air carriers may not have to 
comply with that requirement or similar requirements of their own civil 
aviation authority. EASA, for example, has chosen not to require FRM to 
be retrofitted to in-service airplanes. This AD is intended to require 
any Model 747-400 series passenger airplane that does not have FRM, 
regardless of the rules under which it is operated, to address the FQIS 
latent-plus-one unsafe condition with a corrective action that fully 
complies with the FAA airworthiness standards. This requirement 
fulfills the FAA's International Civil Aviation Organization (ICAO) 
obligation to address unsafe conditions on all of the aircraft 
manufactured by the state of design, not just those aircraft whose 
operation is under the jurisdiction of the state of design. The FAA has 
not changed this AD regarding this issue.

Request To Change Compliance Time

    A4A/CAA requested that the FAA extend the compliance time for the 
modifications specified in paragraphs (g) and (h)(2) of the proposed AD 
to 72 months. The commenter stated that the compliance time should 
match that of AD 2016-07-07 because the unsafe condition and corrective 
actions are similar. A4A/CAA stated that although service information 
was not yet available, the compliance time should align with major 
maintenance schedules, but should be not less than 72 months after 
service information is available.
    Conversely, NATCA recommended that the FAA reject requests for a 
compliance time longer than 5 years as proposed in the NPRM. Assuming 
final rule issuance in 2016, NATCA estimated that a 5-year compliance 
time would result in required compliance by 2021--25 years after the 
TWA Flight 800 fuel tank explosion that led to the requirements in SFAR 
88, and 20 years after issuance of SFAR 88.
    The FAA agrees with A4A/CAA's requests to extend the compliance 
time, and disagrees with NATCA's request. The FAA received similar 
requests to extend the compliance time from several commenters 
regarding the NPRMs for the FQIS modification on other airplanes. The 
FAA disagrees with establishing a compliance time based on issuance of 
the service information that is not yet approved or available. The FAA 
has determined that a 72-month compliance time is appropriate and will 
provide operators adequate time to prepare for and perform the required 
modifications without excessive disruption of operations. The FAA has 
determined that the requested moderate increase in compliance time will 
continue to provide an acceptable level of safety. The FAA has changed 
paragraphs (g) and (h)(2) of this AD accordingly.

Request To Exclude Airplanes To Be Retired

    Virgin Atlantic Airways (VAA) and British Airways (BA) requested 
that the proposed AD be revised to provide dispensation for aircraft to 
be retired. VAA specifically asked for dispensation for aircraft to be 
retired before 2022, noting that a costly retrofit is a real concern 
and a penalty to continued operation of aircraft that are scheduled for 
retirement in the coming years.
    The FAA disagrees with the commenters' request. As previously 
mentioned, the FAA has revised this AD to provide 72 months from the 
effective date of this AD for incorporation of the required 
modification. This compliance time extends several years beyond the 
2022 date requested by VAA, and appears to be beyond the 747-400 fleet 
retirement time planned by BA based on media reports. Therefore, the 
FAA has determined that special dispensation for aircraft to be retired 
is not needed. The FAA has not changed this AD regarding this issue.

Request To Extend Repetitive BITE Check Interval

    Boeing, KLM, and Martinair requested that paragraph (h)(1) of the 
proposed AD be revised to extend the repetitive check interval for the 
BITE checks. Boeing requested that the repetitive interval be extended 
to 750 flight hours to match the repetitive intervals specified in 
Boeing Service Bulletin 747-28-2340, dated June 6, 2014. KLM and 
Martinair requested that the repetitive check interval be extended to 
1,000 flight hours to match A-check intervals.
    The FAA agrees to extend the repetitive check interval to 750 
flight hours to match the repetitive intervals specified in Boeing 
Service Bulletin 747-28-2340, dated June 6, 2014. The FAA intended to 
propose a 750 flight hour interval, but inadvertently specified 650 
flight hour intervals in the proposed AD. The FAA disagrees with 
extending the repetitive check interval to 1,000 flight hours because 
the 750 flight hours was agreed to during discussion of the risk 
assessment and service information for the cargo airplane option with 
Boeing. The FAA has revised paragraph (h)(1) of this AD to specify 
repetitive intervals of 750 flight hours.

Request To Add an Optional Method of Compliance

    Boeing requested that paragraph (h) or (i) of the proposed AD be 
revised to add Boeing Service Bulletin 747-28-2344, dated October 12, 
2018, as an optional method of compliance. Boeing noted that the 
proposed AD does not specify any authority for how to perform the 
required modification. Boeing noted that Boeing Service Bulletin 747-
28-2344, dated October 12, 2018, provides a certified design and 
procedure for accomplishing the wire separation modification and will 
ensure the modification is performed to specified requirements.

[[Page 62987]]

    The FAA agrees with the commenter's request. The FAA has revised 
paragraph (h)(2) of this AD to specify that Boeing Service Bulletin 
747-28-2344, dated October 12, 2018, is an acceptable method of 
compliance. This revision includes adding paragraphs (h)(2)(i) and (ii) 
of this AD. The FAA has also revised the Estimated Costs for 
Alternative Actions table in this final rule to include the estimated 
costs for the inspections and wire separation modification specified in 
Boeing Service Bulletin 747-28-2344, dated October 12, 2018, if 
operators choose to comply using that method.
    The FAA notes that this cost estimate is based on data provided in 
Boeing Service Bulletin 747-28-2344, dated October 12, 2018, while the 
cost estimate provided for a modification using methods approved in 
accordance with the procedures specified in paragraph (h)(2)(i) of this 
AD (paragraph (h)(2) of the proposed AD) is based on data provided by 
the manufacturer for Model 757 and 767 airplanes. The FAA had 
previously determined, as specified in the NPRM, that the work involved 
for the cargo airplane wire separation modification would take 230 
work-hours. Boeing has since provided an updated estimate of 74 work-
hours for the alternative modification for cargo airplanes. The FAA has 
revised the cost estimate for the modification accordingly in this 
final rule.

Request To Address Unsafe Condition on All Fuel Tanks

    NATCA recommended that the FAA require design changes that 
eliminate unsafe FQIS failure conditions on all fuel tanks on the 
affected models, regardless of fuel tank location or the percentage of 
time the fuel tank is flammable. NATCA referred to four fuel tank 
explosions in low-flammability exposure time fuel tanks identified by 
the FAA during FTFR rulemaking. NATCA stated that neither FRM nor 
alternative actions for cargo airplanes (e.g., BITE checks (checks of 
built-in test equipment) followed by applicable repairs before further 
flight and modification of the center fuel tank FQIS wiring within 60 
months) would bring the airplane into full regulatory compliance. NATCA 
added that the combination of failures described in the NPRM meets the 
criteria for ``known combinations'' of failures that require corrective 
action in FAA Policy Memorandum ANM100-2003-112-15.
    The FAA disagrees with the commenter's request. The FAA has 
determined that according to Policy Memorandum ANM100-2003-112-15, the 
failure condition for the airplanes affected by this AD should not be 
classified as a ``known combination.'' While the FQIS design 
architecture is similar to that of the early Boeing Model 747 
configuration that is suspected of contributing to the TWA Flight 800 
fuel tank explosion, significant differences exist in the design of 
FQIS components and wire installations between the affected The Boeing 
Company models and the early Model 747 airplanes such that the intent 
of the ``known combinations'' provision for low-flammability fuel tanks 
in the policy memorandum is not applicable. Therefore, this AD affects 
only the identified Boeing airplanes with high-flammability exposure 
time fuel tanks, as specified in paragraph (c) of this AD. The FAA 
provided a detailed response to similar comments in the preamble of the 
final rule for AD 2016-07-07. The FAA has not changed this final rule 
regarding this issue.

Request To Clarify Certification Basis for Modification Requirements

    NATCA recommended that the FAA revise paragraph (g) of the proposed 
AD to clearly state that the required FQIS design changes must comply 
with the fail-safe requirements of 14 CFR 25.901(c), as amended by 
amendment 25-46 (43 FR 50597, October 30, 1978); and 14 CFR 25.981(a) 
and (b), as amended by amendment 25-102; NATCA added that these 
provisions are required by SFAR 88.
    The FAA does not agree to change paragraph (g) of this AD. While 
the FAA agrees that modifications to comply with paragraph (g) of this 
AD should be required to comply with the referenced regulations, that 
requirement already exists in 14 CFR part 21. No change to this AD is 
necessary.

Request To Require Modification on All Production Airplanes

    NATCA recommended that the FAA require designs that comply with 14 
CFR 25.901(c) and 25.981(a)(3) on all newly produced transport 
airplanes. NATCA stated that continuing to grant exemptions to 14 CFR 
25.901(c), as amended by amendment 25-40 (42 FR 15042, March 17, 1977); 
and 14 CFR 25.981(a)(3), as amended by amendment 25-102; has allowed 
continued production of thousands of airplanes with this known unsafe 
condition.
    The FAA disagrees with the commenter's request. The recommendation 
to require production airplanes to fully comply with 14 CFR 25.901(c) 
and 14 CFR 25.981(a)(3) is outside the scope of this rulemaking. This 
AD applies only to Model 747-400, 747-400D, and 747-400F series 
airplanes, which are no longer in production. In addition, the FAA has 
implemented requirements for all large transport airplanes produced 
after September 2010 to include flammability reduction methods for 
tanks that would otherwise be high-flammability fuel tanks. Boeing 
incorporated this change into the Model 747 series airplanes that are 
still in production and the FAA has excluded those models from the 
applicability of this AD. The FAA has not changed this final rule 
regarding this issue.

Request To State That an Exemption Is Required

    Boeing requested that paragraph (h) of the proposed AD be revised 
to state that an exemption is required to accomplish the specified 
actions. Boeing stated that the FAA has identified that the BITE 
procedure and wire separation design changes specified in the proposed 
AD are not sufficient for compliance to 14 CFR 25.981(a) at the FQIS 
level. Boeing stated that an exemption is therefore needed prior to 
approval of the related design change.
    The FAA agrees to clarify. The BITE check is not a type design 
change or alteration, so no exemption from the airworthiness standards 
is required for that action. The design data approval of any partial 
wire separation modification would require an exemption. That exemption 
would be obtained by the party seeking approval of the alteration data, 
and no further exemption would be required for the party using that 
data to alter an aircraft. Obtaining such an exemption would be part of 
the certification process for such a change, so the FAA does not find 
it necessary to include such information in paragraph (h) of this AD. 
In addition, some parties may choose to comply with the AD using a 
design change that fully complies with the airworthiness standards. The 
FAA also notes that the commenter appears to misunderstand why an 
exemption is needed for the required modification. The exemption is 
needed because, even with the modification, the FQIS does not comply 
with 14 CFR 25.901(c) and 14 CFR 25.981(a). The exemption does not 
authorize evaluation of a partial system for compliance with the system 
level requirement. The FAA has not changed this AD regarding this 
issue.

Request To Provide Cost-Effective Method of Compliance

    Korean Air Lines (KAL), VAA, KLM, and BA requested that the FAA 
encourage Boeing to provide a cost-effective method of compliance for 
passenger airplanes. KAL noted that the

[[Page 62988]]

proposed AD does not provide a clear means of compliance for the 
modification, such as a Boeing service bulletin. KAL and VAA noted that 
the majority of non-FAA operators are not required to retrofit the NGS 
system. The commenters requested that the FAA encourage Boeing to 
develop an acceptable cost-effective method of compliance that does not 
require installation of an NGS. KLM and Martinair also noted that EASA 
only adopted the FAA operational requirement to equip an FRM on newly 
delivered airplanes.
    The FAA agrees that the lack of service information for FQIS 
modifications makes it difficult to assess the required work to modify 
the FQIS, and acknowledges the high cost of NGS. However, the FAA 
disagrees with the commenters' request. For passenger-carrying 
airplanes, the cost per airplane of providing a modification of the 
FQIS that fully complies with the airworthiness standards was estimated 
by Boeing and their FQIS vendor (Goodrich) prior to the issuance of the 
NPRM to be comparable to the cost of installing NGS. Based on that cost 
estimate, Boeing proposed that they not be required to develop a fully 
compliant FQIS modification for passenger airplanes because it would 
not provide significant savings to operators and NGS would provide a 
greater safety benefit. The FAA agreed.
    The FAA's understanding is that Boeing's current position is the 
same, and that they do not plan to develop a fully compliant FQIS 
modification for passenger airplanes to address paragraph (g) of this 
AD. However, if service information is developed, approved, and 
available in the future, operators may request approval under the 
provisions of paragraph (i) of this AD to use approved service 
instructions as an AMOC for the requirements of this AD, or the FAA may 
approve the service information as a global AMOC for this AD. In 
addition, as noted previously, Boeing has issued Service Bulletin 747-
28-2344, dated October 12, 2018, for all-cargo airplanes, and the FAA 
has revised paragraph (h)(2)(ii) of this AD to specify that Boeing 
Service Bulletin 747-28-2344, dated October 12, 2018, is an acceptable 
method of compliance.

Request To Require Design Changes From Manufacturers

    NATCA recommended that the FAA follow the agency's compliance and 
enforcement policy to require manufacturers to develop the necessary 
design changes soon enough to support operators' ability to comply with 
the proposed requirements. NATCA noted that SFAR 88 required 
manufacturers to develop all design changes for unsafe conditions 
identified by their SFAR 88 design reviews by December 2002, or within 
an additional 18 months if the FAA granted an extension.
    The FAA acknowledges the commenter's concerns. However, any 
enforcement action is outside the scope of this rulemaking. The FAA has 
not changed this final rule regarding this issue.

Clarification of BITE Check Compliance Time

    The FAA has revised paragraph (h)(1) of this AD to clarify the 
compliance time for the BITE check relative to the requirement to 
record the fault codes. The FAA recognized that operators might 
interpret the proposed requirements for alternative actions for cargo 
airplanes as allowing additional flights prior to performing the BITE 
check after first recording the fault codes. The FAA intended for 
operators to perform the BITE check immediately after recording the 
fault codes to address both the fault codes that exist prior to 
performing the BITE check and any new codes that are identified during 
the BITE check.

Clarification of Applicability

    The FAA has revised paragraph (c) of this AD to clarify that 
airplanes equipped with an ignition mitigation means (IMM) approved by 
the FAA as compliant with certain regulations are excluded from this 
AD. This revision includes adding paragraphs (c)(1) and (2) of this AD. 
The FAA intended for airplanes with compliant IMM to be excluded from 
the actions required by this AD. The FAA has determined that the 
installation of an approved IMM provides a level of risk reduction at 
least as great as that provided by FRM and adequately addresses the 
unsafe condition.

Conclusion

    The FAA reviewed the relevant data, considered the comments 
received, and determined that air safety and the public interest 
require adopting this final rule with the changes described previously 
and minor editorial changes. The FAA has determined that these minor 
changes:
     Are consistent with the intent that was proposed in the 
NPRM for addressing the unsafe condition; and
     Do not add any additional burden upon the public than was 
already proposed in the NPRM.
    The FAA also determined that these changes will not increase the 
economic burden on any operator or increase the scope of this final 
rule.

Related Service Information Under 1 CFR Part 51

    The FAA reviewed Boeing Service Bulletin 747-28-2340, dated June 6, 
2014. This service information describes procedures for a BITE check 
(check of built-in test equipment) of the FQIS.
    The FAA also reviewed Boeing Service Bulletin 747-28-2344, dated 
October 12, 2018. This service information describes procedures for a 
general visual inspection for any damage to the FQIS wire bundle, 
repair of damaged FQIS wire bundles, and modification of the airplane 
by separating FQIS wiring that runs between the FQIS processor and the 
center tank wing spar penetrations from other airplane wiring.
    This service information is reasonably available because the 
interested parties have access to it through their normal course of 
business or by the means identified in the ADDRESSES section.

Costs of Compliance

    The FAA estimates that this AD affects 71 airplanes of U.S. 
registry. The FAA estimates the following costs to comply with this AD:

                                      Estimated Costs for Required Actions
----------------------------------------------------------------------------------------------------------------
                                                                                     Cost per      Cost on U.S.
               Action                         Labor cost            Parts cost        product        operators
----------------------------------------------------------------------------------------------------------------
Modification.......................  1,200 work-hours x $85 per         $200,000        $302,000     $21,442,000
                                      hour = $102,000.
----------------------------------------------------------------------------------------------------------------


[[Page 62989]]


                                     Estimated Costs for Alternative Actions
----------------------------------------------------------------------------------------------------------------
                Action                            Labor cost              Parts cost        Cost per product
----------------------------------------------------------------------------------------------------------------
BITE check............................  1 work-hours x $85 per hour =               $0  $340 per year (4 checks
                                         $85 per check.                                  per year).
Inspection and wire separation (using   Up to 41 work-hours x $85 per            4,220  Up to $8,065.
 service information).                   hour = Up to $3,845.
Wire separation.......................  74 work hours x $85 per hour =          10,000  $16,290.
                                         $6,290.
----------------------------------------------------------------------------------------------------------------

    The FAA has received no definitive data that would enable us to 
provide cost estimates for the on-condition actions specified in this 
AD.

Authority for This Rulemaking

    Title 49 of the United States Code specifies the FAA's authority to 
issue rules on aviation safety. Subtitle I, section 106, describes the 
authority of the FAA Administrator. Subtitle VII: Aviation Programs, 
describes in more detail the scope of the Agency's authority.
    The FAA is issuing this rulemaking under the authority described in 
Subtitle VII, Part A, Subpart III, Section 44701: General requirements. 
Under that section, Congress charges the FAA with promoting safe flight 
of civil aircraft in air commerce by prescribing regulations for 
practices, methods, and procedures the Administrator finds necessary 
for safety in air commerce. This regulation is within the scope of that 
authority because it addresses an unsafe condition that is likely to 
exist or develop on products identified in this rulemaking action.

Regulatory Findings

    This AD will not have federalism implications under Executive Order 
13132. This AD will not have a substantial direct effect on the States, 
on the relationship between the national government and the States, or 
on the distribution of power and responsibilities among the various 
levels of government.
    For the reasons discussed above, I certify that this AD:
    (1) Is not a ``significant regulatory action'' under Executive 
Order 12866,
    (2) Will not affect intrastate aviation in Alaska, and
    (3) Will not have a significant economic impact, positive or 
negative, on a substantial number of small entities under the criteria 
of the Regulatory Flexibility Act.

List of Subjects in 14 CFR Part 39

    Air transportation, Aircraft, Aviation safety, Incorporation by 
reference, Safety.

Adoption of the Amendment

    Accordingly, under the authority delegated to me by the 
Administrator, the FAA amends 14 CFR part 39 as follows:

PART 39--AIRWORTHINESS DIRECTIVES

0
1. The authority citation for part 39 continues to read as follows:

    Authority: 49 U.S.C. 106(g), 40113, 44701.


Sec.  39.13  [Amended]

0
2. The FAA amends Sec.  39.13 by adding the following new airworthiness 
directive (AD):

2020-18-02 The Boeing Company: Amendment 39-21223; Docket No. FAA-
2016-6145; Product Identifier 2015-NM-056-AD.

(a) Effective Date

    This AD is effective November 10, 2020.

(b) Affected ADs

    None.

(c) Applicability

    This AD applies to The Boeing Company Model 747-400, -400D, and 
-400F series airplanes, certificated in any category, excluding the 
airplanes identified in paragraphs (c)(1) and (2) of this AD.
    (1) Airplanes equipped with a flammability reduction means (FRM) 
approved by the FAA as compliant with the fuel tank flammability 
reduction (FTFR) requirements of 14 CFR 25.981(b) or 26.33(c)(1).
    (2) Airplanes equipped with an ignition mitigation means (IMM) 
approved by the FAA as compliant with the FTFR requirements of 14 
CFR 25.981(c) or 26.33(c)(2).

(d) Subject

    Air Transport Association (ATA) of America Code 28, Fuel.

(e) Unsafe Condition

    This AD was prompted by the FAA's analysis of the Model 747 fuel 
system reviews conducted by the manufacturer. The FAA is issuing 
this AD to prevent ignition sources inside the center fuel tank, 
which, in combination with flammable fuel vapors, could result in a 
fuel tank explosion and consequent loss of the airplane.

(f) Compliance

    Comply with this AD within the compliance times specified, 
unless already done.

(g) Modification

    Within 72 months after the effective date of this AD, modify the 
fuel quantity indicating system (FQIS) to prevent development of an 
ignition source inside the center fuel tank due to electrical fault 
conditions, using a method approved in accordance with the 
procedures specified in paragraph (i) of this AD.

(h) Alternative Actions for Cargo Airplanes

    For airplanes used exclusively for cargo operations: As an 
alternative to the requirements of paragraph (g) of this AD, do the 
actions specified in paragraphs (h)(1) and (2) of this AD. To 
exercise this alternative, operators must perform the first 
inspection required under paragraph (h)(1) of this AD within 6 
months after the effective date of this AD. To exercise this 
alternative for airplanes returned to service after conversion of 
the airplane from a passenger configuration to an all-cargo 
configuration more than 6 months after the effective date of this 
AD, operators must perform the first inspection required under 
paragraph (h)(1) of this AD prior to further flight after the 
conversion.
    (1) Within 6 months after the effective date of this AD, record 
the existing fault codes stored in the FQIS processor and before 
further flight thereafter do a BITE check (check of built-in test 
equipment) of the FQIS, in accordance with the Accomplishment 
Instructions of Boeing Service Bulletin 747-28-2340, dated June 6, 
2014. If any nondispatchable fault code is recorded prior to the 
BITE check or as a result of the BITE check, before further flight, 
do all applicable repairs and repeat the BITE check until a 
successful test is performed with no nondispatchable faults found, 
in accordance with the Accomplishment Instructions of Boeing Service 
Bulletin 747-28-2340, dated June 6, 2014. Repeat these actions 
thereafter at intervals not to exceed 750 flight hours. Modification 
as specified in paragraph (h)(2) of this AD does not terminate the 
repetitive BITE check requirement of this paragraph.
    (2) Within 72 months after the effective date of this AD, do the 
actions specified in paragraph (h)(2)(i) or (ii) of this AD.
    (i) Modify the airplane by separating FQIS wiring that runs 
between the FQIS processor and the center tank wing spar 
penetrations, including any circuits that might pass through a main 
fuel tank, from other airplane wiring that is not intrinsically safe 
using methods approved in accordance with the procedures specified 
in paragraph (i) of this AD.
    (ii) Do a general visual inspection for any damage to the FQIS 
wire bundle and all

[[Page 62990]]

applicable repairs; and modify the airplane by separating FQIS 
wiring that runs between the FQIS processor and the center tank wing 
spar penetrations, including any circuits that might pass through a 
main fuel tank, from other airplane wiring that is not intrinsically 
safe; in accordance with the Accomplishment Instructions of Boeing 
Service Bulletin 747-28-2344, dated October 12, 2018. Do all 
applicable repairs before further flight.

(i) Alternative Methods of Compliance (AMOCs)

    (1) The Manager, Seattle ACO Branch, FAA, has the authority to 
approve AMOCs for this AD, if requested using the procedures found 
in 14 CFR 39.19. In accordance with 14 CFR 39.19, send your request 
to your principal inspector or local Flight Standards District 
Office, as appropriate. If sending information directly to the 
manager of the certification office, send it to the attention of the 
person identified in paragraph (j)(1) of this AD. Information may be 
emailed to: [email protected].
    (2) Before using any approved AMOC, notify your appropriate 
principal inspector, or lacking a principal inspector, the manager 
of the local flight standards district office/certificate holding 
district office.
    (3) An AMOC that provides an acceptable level of safety may be 
used for any repair, modification, or alteration required by this AD 
if it is approved by The Boeing Company Organization Designation 
Authorization (ODA) that has been authorized by the Manager, Seattle 
ACO Branch, FAA, to make those findings. To be approved, the repair 
method, modification deviation, or alteration deviation must meet 
the certification basis of the airplane, and the approval must 
specifically refer to this AD.
    (4) For service information that contains steps that are labeled 
as Required for Compliance (RC), the provisions of paragraphs 
(i)(4)(i) and (ii) of this AD apply.
    (i) The steps labeled as RC, including substeps under an RC step 
and any figures identified in an RC step, must be done to comply 
with the AD. If a step or substep is labeled ``RC Exempt,'' then the 
RC requirement is removed from that step or substep. An AMOC is 
required for any deviations to RC steps, including substeps and 
identified figures.
    (ii) Steps not labeled as RC may be deviated from using accepted 
methods in accordance with the operator's maintenance or inspection 
program without obtaining approval of an AMOC, provided the RC 
steps, including substeps and identified figures, can still be done 
as specified, and the airplane can be put back in an airworthy 
condition.

(j) Related Information

    (1) For more information about this AD, contact Jon Regimbal, 
Aerospace Engineer, Propulsion Section, FAA, Seattle ACO Branch, 
2200 South 216th St., Des Moines, WA 98198; phone and fax: 206-231-
3557; email: [email protected].
    (2) Service information identified in this AD that is not 
incorporated by reference is available at the addresses specified in 
paragraphs (k)(3) and (4) of this AD.

(k) Material Incorporated by Reference

    (1) The Director of the Federal Register approved the 
incorporation by reference (IBR) of the service information listed 
in this paragraph under 5 U.S.C. 552(a) and 1 CFR part 51.
    (2) You must use this service information as applicable to do 
the actions required by this AD, unless the AD specifies otherwise.
    (i) Boeing Service Bulletin 747-28-2340, dated June 6, 2014.
    (ii) Boeing Service Bulletin 747-28-2344, dated October 12, 
2018.
    (3) For service information identified in this AD, contact 
Boeing Commercial Airplanes, Attention: Contractual & Data Services 
(C&DS), 2600 Westminster Blvd., MC 110 SK57, Seal Beach, CA 90740-
5600; telephone 562-797-1717; internet https://www.myboeingfleet.com.
    (4) You may view this service information at the FAA, 
Airworthiness Products Section, Operational Safety Branch, 2200 
South 216th St., Des Moines, WA. For information on the availability 
of this material at the FAA, call 206-231-3195.
    (5) You may view this service information that is incorporated 
by reference at the National Archives and Records Administration 
(NARA). For information on the availability of this material at 
NARA, email [email protected], or go to: https://www.archives.gov/federal-register/cfr/ibr-locations.html.

    Issued on August 19, 2020.
Gaetano A. Sciortino,
Deputy Director for Strategic Initiatives, Compliance & Airworthiness 
Division, Aircraft Certification Service.
[FR Doc. 2020-21996 Filed 10-5-20; 8:45 am]
BILLING CODE 4910-13-P