[Federal Register Volume 60, Number 49 (Tuesday, March 14, 1995)]
[Rules and Regulations]
[Pages 13618-13620]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-5781]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-123-AD; Amendment 39-9172; AD 95-06-02]


Airworthiness Directives; Boeing Model 747 Series Airplanes, 
Excluding Airplanes Equipped With Pratt & Whitney PW4000 and General 
Electric CF6-80C2 Series Engines

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment adopts a new airworthiness directive (AD), 
applicable to certain Boeing Model 747 series airplanes, that requires 
replacement of certain fuse pins on the upper link of the inboard and 
outboard struts. This AD would also require inspections to detect 
corrosion or cracks of certain fuse pins, and replacement, if 
necessary. This amendment is prompted by reports of cracked or corroded 
fuse pins on the upper link of the inboard and outboard struts, which 
could result in fracturing of the pins. The actions specified by this 
AD are intended to prevent failure of the strut and separation of an 
engine from the airplane due to fracturing of the fuse pins.

DATES: Effective April 13, 1995.
    The incorporation by reference of certain publications listed in 
the regulations is approved by the Director of the Federal Register as 
of April 13, 1995.

ADDRESSES: The service information referenced in this AD may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the Federal 
Aviation Administration (FAA), Transport Airplane Directorate, Rules 
Docket, 1601 Lind Avenue SW., Renton, Washington; or at the Office of 
the Federal Register, 800 North Capitol Street NW., suite 700, 
Washington, DC.

FOR FURTHER INFORMATION CONTACT: Tim Backman, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue SW., Renton, Washington 
98055-4056; telephone (206) 227-2776; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) to include an airworthiness 
directive (AD) that is applicable to certain Boeing Model 747 series 
airplanes was published in the Federal Register on November 10, 1994 
(59 FR 56008). That action proposed to require replacement of bottle 
bore style fuse pins, installed in the forward position of the upper 
link on the inboard and outboard struts, with either third generation 
fuse pins or new bulkhead style pins. That action also proposed to 
require repetitive detailed visual inspections to detect corrosion of 
bulkhead style fuse pins; magnetic particle inspections to detect 
cracks in those pins; and replacement of any corroded or cracked 
bulkhead style fuse pin with a third generation fuse pin or with a new 
bulkhead style pin. Installation of a third generation fuse pin, if 
accomplished, would constitute terminating action for the inspection 
requirements of the proposed AD.
    Interested persons have been afforded an opportunity to participate 
in the making of this amendment. Due consideration has been given to 
the two comments received.
    Both commenters support the proposed rule.
    After careful review of the available data, including the comments 
noted above, the FAA has determined that air safety and the public 
interest require the adoption of the rule as proposed.
    There are approximately 869 Model 747 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 147 
airplanes of U.S. registry will be affected by this AD, that it will 
take approximately 122 work hours per airplane to accomplish the 
replacement of fuse pins with bulkhead style pins, and that the average 
labor rate is $60 per work hour. Based on these figures, the total cost 
impact on U.S. operators who replace fuse pins with bulkhead style pins 
is estimated to be $7,320 per airplane.
    It will take approximately 140 work hours per airplane to 
accomplish the replacement of fuse pins with third generation pins. The 
average labor rate is $60 per work hour. Based on these figures, the 
total cost impact on U.S. operators who replace fuse pins with third 
generation pins is estimated to be $8,400 per airplane.
    It will take approximately 1.5 work hours per airplane to 
accomplish the inspections (in addition to the work hours necessary for 
fuse pin replacement). The average labor rate is $60 per work hour. 
Based on these figures, the total cost impact on U.S. operators for the 
required inspections is estimated to be $90 per airplane per 
inspection.
    The cost of required replacement parts will vary from airplane to 
airplane, depending upon the current airplane configuration.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    The number of required work hours, as indicated above, is presented 
as if the accomplishment of the inspection and replacement actions were 
to be conducted as ``stand alone'' actions. However, in actual 
practice, these actions, for the most part, would be accomplished 
coincidentally or in combination with normally scheduled airplane 
inspections and other maintenance program tasks. Therefore, the actual 
number of necessary additional work hours would be minimal in many 
instances. Additionally, any costs associated with special airplane 
scheduling would be minimal.
    The FAA recognizes that the obligation to maintain aircraft in an 
airworthy condition is vital, but sometimes expensive. Because AD's 
require specific actions to address specific unsafe conditions, they 
appear to impose costs that would not otherwise be borne by operators. 
[[Page 13619]] However, because of the general obligation of operators 
to maintain aircraft in an airworthy condition, this appearance is 
deceptive. Attributing those costs solely to the issuance of this AD is 
unrealistic because, in the interest of maintaining safe aircraft, 
prudent operators would accomplish the required actions even if they 
were not required to do so by the AD.
    A full cost-benefit analysis has not been accomplished for this AD. 
As a matter of law, in order to be airworthy, an aircraft must conform 
to its type design and be in a condition for safe operation. The type 
design is approved only after the FAA makes a determination that it 
complies with all applicable airworthiness requirements. In adopting 
and maintaining those requirements, the FAA has already made the 
determination that they establish a level of safety that is cost-
beneficial. When the FAA, as in this AD, makes a finding of an unsafe 
condition, this means that the original cost-beneficial level of safety 
is no longer being achieved and that the required actions are necessary 
to restore that level of safety. Because this level of safety has 
already been determined to be cost-beneficial, a full cost-benefit 
analysis for this AD would be redundant and unnecessary.
    The regulations adopted herein will not have substantial direct 
effects 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. Therefore, in 
accordance with Executive Order 12612, it is determined that this final 
rule does not have sufficient federalism implications to warrant the 
preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this action (1) is 
not a ``significant regulatory action'' under Executive Order 12866; 
(2) is not a ``significant rule'' under DOT Regulatory Policies and 
Procedures (44 FR 11034, February 26, 1979); 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. A final evaluation has been prepared for this action 
and it is contained in the Rules Docket. A copy of it may be obtained 
from the Rules Docket at the location provided under the caption 
ADDRESSES.

List of Subjects in 14 CFR Part 39

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

Adoption of the Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration amends part 39 of 
the Federal Aviation Regulations (14 CFR part 39) as follows:

PART 39--AIRWORTHINESS DIRECTIVES

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

    Authority: 49 U.S.C. App. 1354(a), 1421 and 1423; 49 U.S.C. 
106(g); and 14 CFR 11.89.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by adding the following new 
airworthiness directive:

95-06-02  Boeing: Amendment 39-9172. Docket 94-NM-123-AD.

    Applicability: Model 747 series airplanes, line numbers 1 
through 967 inclusive, and 969 through 922 inclusive; excluding 
airplanes equipped with Pratt & Whitney PW4000 or General Electric 
CF6-80C2 series engines; certificated in any category.

    Note 1: This AD does not require that the actions be 
accomplished on the struts of airplanes having straight bore fuse 
pins (installed on Model 747 series airplanes equipped with Pratt & 
Whitney PW4000 or General Electric CF6-80C2 series engines) or 15-5 
corrosion resistant steel (third generation) fuse pins.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the strut and loss of an engine due to 
corrosion or cracking of the fuse pins, accomplish the following:
    (a) For airplanes having bottle bore style fuse pins in the 
forward position on the upper link: Replace any bottle bore style 
fuse pin with a new bulkhead style fuse pin in the forward position, 
or with 15-5 corrosion resistant steel (third generation) fuse pins 
in the forward position, in accordance with Boeing Alert Service 
Bulletin 747-54A2166, dated April 28, 1994, at the later of the 
times specified in paragraphs (a)(1) and (a)(2) of this AD.
    (1) Prior to the accumulation of 5,000 landings on the fuse pin, 
or within 5 years since installation of the pin, whichever occurs 
first. Or
    (2) Within 6 months after the effective date of this AD.

    Note 2: Third generation fuse pins are installed in pairs (in 
the forward and aft positions). Therefore, replacement of an 
individual upper link fuse pin in the forward position with a third 
generation pin also would necessitate replacement of the pin in the 
aft position.

    Note 3: The alert service bulletin references Boeing Service 
Bulletin 747-54-2155, dated September 23, 1993, as an additional 
source of service information for replacement of the fuse pins with 
15-5 corrosion resistant steel (third generation) fuse pins. 
Installation of these third generation fuse pins is preferred over 
installation of bulkhead style fuse pins.

    (b) For airplanes having bulkhead style fuse pins in the forward 
position on the upper link: Perform a detailed visual inspection to 
detect corrosion of the pins, and a magnetic particle inspection to 
detect cracks, in accordance with Boeing Alert Service Bulletin 747-
54A2166, dated April 28, 1994, at the later of the times specified 
in paragraphs (b)(1) and (b)(2) of this AD.
    (1) Prior to the accumulation of 8,000 landings on the fuse pin, 
or within 8 years since installation of the pin, whichever occurs 
first. Or
    (2) Within 12 months after the effective date of this AD.
    (c) If no corrosion or crack is found during the inspection 
required by paragraph (b) of this AD, repeat the inspections 
thereafter at the intervals specified in paragraph (c)(1) or (c)(2) 
of this AD, as applicable.
    (1) For the inboard and outboard struts on airplanes other than 
those identified in paragraph (c)(2) of this AD: Repeat the 
inspections at intervals not to exceed 1,000 landings.
    (2) For the outboard struts on airplanes equipped with Rolls-
Royce RB211-524G or -524H series engines: Repeat the inspections at 
intervals not to exceed 2,000 landings.

    Note 4: The outboard struts of airplanes equipped with Rolls-
Royce RB211-524G or -524H series engines are equipped with thick 
wall ``4330 steel'' bulkhead style fuse pins in the forward position 
of the upper link. Crack propagation to critical length in these 
thick wall pins is slower than for pins installed on the struts of 
airplanes equipped with engines other than the Rolls-Royce RB211-
524G or -524H series.

    (d) If any corrosion or crack is found during any inspection 
required by this AD, prior to further flight, replace the corroded 
or cracked pin with either a new bulkhead style fuse pin in the 
forward position of the upper link, or with 15-5 corrosion resistant 
steel (third generation) fuse pins in the forward and aft positions 
of the upper link, in accordance with Boeing Alert Service Bulletin 
747-54A2166, dated April 28, 1994.
    (1) If the corroded or cracked fuse pin is replaced with a new 
bulkhead style fuse pin, prior to the accumulation of 8,000 landings 
on the new pin, or within 8 years since installation of the new pin, 
whichever occurs first, perform a detailed visual inspection to 
detect corrosion of the new pin, and a magnetic particle inspection 
to detect cracks of the new pin, in accordance with Boeing Alert 
Service Bulletin 747-54A2166, dated April 28, 1994. Repeat these 
inspections thereafter at the interval specified in paragraph 
(d)(1)(i) or (d)(1)(ii) of this AD, as applicable.
    (i) For the inboard and outboard struts on airplanes other than 
those identified in paragraph (d)(1)(ii) of this AD: Repeat the 
inspections at intervals not to exceed 1,000 landings.
    (ii) For the outboard struts on airplanes equipped with Rolls-
Royce RB211-524G or -524H series engines: Repeat the inspections at 
intervals not to exceed 2,000 landings.
    (2) If the corroded or cracked fuse pin is replaced with a 15-5 
corrosion resistant steel [[Page 13620]] (third generation) fuse 
pin, no further action is required by this AD.
    (e) Installation of 15-5 corrosion resistant steel (third 
generation) fuse pins in the forward and aft positions of the upper 
link on the inboard or outboard strut constitutes terminating action 
for the requirements of this AD.
    (f) An alternative method of compliance or adjustment of the 
compliance time that provides an acceptable level of safety may be 
used if approved by the Manager, Manager, Seattle Aircraft 
Certification Office (ACO), FAA, Transport Airplane Directorate. 
Operators shall submit their requests through an appropriate FAA 
Principal Maintenance Inspector, who may add comments and then send 
it to the Manager, Manager, Seattle ACO.

    Note 5: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (g) Special flight permits may be issued in accordance with 
sections 21.197 and 21.199 of the Federal Aviation Regulations (14 
CFR 21.197 and 21.199) to operate the airplane to a location where 
the requirements of this AD can be accomplished.
    (h) The replacement, inspections, and installation shall be done 
in accordance with Boeing Alert Service Bulletin 747-54A2166, dated 
April 28, 1994. This incorporation by reference was approved by the 
Director of the Federal Register in accordance with 5 U.S.C. 552(a) 
and 1 CFR part 51. Copies may be obtained from Boeing Commercial 
Airplane Group, P.O. Box 3707, Seattle, Washington 98124-2207. 
Copies may be inspected at the FAA, Transport Airplane Directorate, 
1601 Lind Avenue, SW., Renton, Washington; or at the Office of the 
Federal Register, 800 North Capitol Street NW., suite 700, 
Washington, DC.
    (i) This amendment becomes effective on April 13, 1995.

    Issued in Renton, Washington, on March 3, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-5781 Filed 3-13-95; 8:45 am]
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