[Federal Register Volume 62, Number 93 (Wednesday, May 14, 1997)]
[Rules and Regulations]
[Pages 26381-26383]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 97-12682]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 97-NM-12-AD; Amendment 39-10027; AD 96-26-52 R1]
RIN 2120-AA64


Airworthiness Directives; Boeing Model 747 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule.

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SUMMARY: This amendment revises an existing airworthiness directive 
(AD), applicable to certain Boeing Model 747 series airplanes, that 
currently requires repetitive inspections of the access doors to the 
midspar/spring beam fuse pins on all engine pylons to detect cracks on 
the external surface; repetitive inspections of each midspar/spring 
beam fuse pin to detect if it protrudes beyond its mating nut by a 
specified distance; and repair of any discrepancy found. The actions 
specified by that AD are intended to prevent migration of this fuse 
pin, which, if not detected and corrected in a timely manner, could 
result in failure of the engine pylon and consequent separation of the 
engine from the wing. This amendment increases the intervals between 
inspections of the access doors and each midspar/spring beam fuse pin, 
and consequently decreases the frequency of inspections. This amendment 
is prompted by new data provided by the manufacturer indicating that 
the reported migration of the fuse pin was apparently the result of an 
incorrectly installed nut.

EFFECTIVE DATE: June 18, 1997.

ADDRESSES: Information concerning this amendment may be obtained from 
or 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: Tamara Dow, Aerospace 
Engineer,Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification 
Office, 1601 Lind Avenue, SW., Renton, Washington; telephone (425) 227-
2771; fax (425) 227-1181.

SUPPLEMENTARY INFORMATION: A proposal to amend part 39 of the Federal 
Aviation Regulations (14 CFR part 39) by revising AD 96-26-52, 
amendment 39-9868 (62 FR 302, January 3, 1997), which is applicable to 
certain Boeing Model 747 series airplanes, was published in the Federal 
Register on February 12, 1997 (62 FR 6499). That action proposed to 
continue to require repetitive inspections of the access doors to the 
midspar/spring beam fuse pins on all engine pylons to detect cracks on 
the external surface, repetitive inspections of each midspar/spring 
beam fuse pin to detect if it protrudes beyond its mating nut by a 
specified distance, and repair of any discrepancy found. That action 
also proposed to increase the intervals between inspections of the 
access doors and each midspar/spring beam fuse pin, and consequently 
decrease the frequency of inspections.

Comments on the Proposal

    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.
    One commenter supports the proposal.
    One commenter requests that the proposed frequency of repetitive 
inspections of the access doors to each midspar/spring beam fuse pin 
and each fuse pin be altered to 5,000 hours time-in-service, or 15 
months, whichever occurs first; this interval is equivalent to the 
maintenance interval specified in the operator's Maintenance 
ReviewBoard (MRB) report. The commenter considers that adoption of the 
FAA's proposed interval of 1,000 landings or 18 months, whichever 
occurs first, would require certain operators to schedule special times 
for the accomplishment of this inspection.
    The FAA concurs that the compliance times can be revised somewhat. 
The

[[Page 26382]]

FAA's intent was that inspections be conducted during a regularly 
scheduled maintenance visit for the majority of the affected fleet, 
when the airplanes would be located at a base where special equipment 
and trained personnel would be readily available, if necessary. Based 
on the information supplied by the commenter, the FAA recognizes that 
5,000 hours time-in-service corresponds closely to the interval 
specified in the operators' MRB report. In light of this, the FAA has 
revised paragraphs (a)(1)(i), (a)(2)(i), and (a)(2)(ii) of the final 
rule to reflect a compliance time of ``intervals not to exceed 1,000 
landings or 5,000 hours time-in-service, whichever occurs later, but 
not to exceed 18 months.'' The FAA does not consider that this revision 
of the compliance time will adversely affect safety.

Conclusion

    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 with the changes previously 
described. The FAA has determined that these changes will neither 
increase the economic burden on any operator nor increase the scope of 
the AD.

Cost Impact

    There are approximately 459 Boeing Model 747 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 44 
airplanes of U.S. registry will be affected by this AD.
    It will take approximately 4 work hours per airplane to accomplish 
each cycle of required inspections, at an average rate of $60 per work 
hour. Based on these figures, the cost impact of the AD on U.S. 
operators is estimated to be $10,560 per inspection cycle, or $240 per 
airplane, per inspection cycle. (By increasing the intervals between 
inspections, this AD will result in inspections being conducted less 
frequently than is now required.)
    The 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.

Regulatory Impact

    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, 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. 106(g), 40113, 44701.

Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-9868 (62 FR 
302, January 3, 1997), and by adding a new airworthiness directive 
(AD), amendment 39-10027, to read as follows:

96-26-52 R1 BOEING: Amendment 39-10027. Docket 97-NM-12-AD. Revises 
AD 96-26-52, Amendment 39-9868.

    Applicability: Model 747 series airplanes having line numbers 1 
through 1046 inclusive; certificated in any category; that meet all 
of the following criteria:
     Equipped with Pratt & Whitney Model PW4000 series 
engines, or General Electric Model CF6-80C2 series engines, or Rolls 
Royce Model RB211 series engines;
     On which fuse pins having part numbers 310U2301-101, -
116, -117, or -120 (``third generation'' fuse pins) are installed at 
the midspar/spring beam fittings of the engine pylon; and
     On which the modification of the nacelle strut and wing 
structure in accordance with Boeing Alert Service Bulletin 747-
54A2156 or Boeing Alert Service Bulletin 747-54A2157, as applicable, 
has not been accomplished.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise modified, altered, or repaired in the area subject to the 
requirements of this AD. For airplanes that have been modified, 
altered, or repaired so that the performance of the requirements of 
this AD is affected, the owner/operator must request approval for an 
alternative method of compliance in accordance with paragraph (c) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.
    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent failure of the engine pylon and consequent separation 
of the engine from the wing, due to migration of the fuse pins 
installed at the midspar/spring beam fittings of the pylon, 
accomplish the following:
    (a) Within 15 days after January 8, 1997 (the effective date of 
AD 96-26-52, amendment 39-9868), accomplish the requirements of 
paragraphs (a)(1) and (a)(2) of this AD.
    (1) Perform a detailed visual inspection of the access doors to 
each midspar/spring beam fuse pin on each engine pylon to detect 
cracks on the external surface of the doors.
    (i) If no cracking is detected during the inspection, repeat 
that inspection at intervals not to exceed 1,000 landings or 5,000 
hours time-in-service, whichever occurs later, but not to exceed 18 
months.
    (ii) If any cracking is detected during the inspection, prior to 
further flight, repair in accordance with a method approved by the 
Manager, Seattle Aircraft Certification Office (ACO), FAA, Transport 
Airplane Directorate. Thereafter, repeat the inspection at intervals 
not to exceed 1,000 landings or 5,000 hours time-in-service, 
whichever occurs later, but not to exceed 18 months.
    (2) Gain access through the aft fairing doors of each engine 
pylon to each midspar/spring beam fuse pin and its mating, self-
locking nut, and perform a detailed visual inspection of each fuse 
pin to verify that at least one thread of the fuse pin protrudes 
beyond its mating, self-locking nut.
    (i) If no discrepancy is detected during the inspection, repeat 
that inspection at intervals not to exceed 1,000 landings or 5,000 
hours time-in-service, whichever occurs later, but not to exceed 18 
months.
    (ii) If the inspection reveals that at least one thread does not 
protrude beyond its mating, self-locking nut, prior to further 
flight, repair in accordance with a method approved by the Manager, 
Seattle ACO. Thereafter, repeat the inspection at intervals not to 
exceed 1,000 landings or 5,000 hours time-in-service, whichever 
occurs later, but not to exceed 18 months.
    (b) Accomplishment of the modification of the nacelle strut and 
wing structure in accordance with Boeing Alert Service Bulletin 747-
54A2156, Revision 2, dated December 21, 1995, or earlier revisions 
(for airplanes equipped with General Electric Model CF6-80C2 series 
engines, or Pratt & Whitney PW4000 series engines); or Boeing

[[Page 26383]]

Alert Service Bulletin 747-54A2157, Revision 2, dated November 14, 
1996, or earlier revisions (for airplanes with Rolls Royce Model 
RB211 series engines); as applicable; constitutes terminating action 
for the repetitive detailed visual inspections required by 
paragraphs (a)(1) and (a)(2) of this AD.
    (c) 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, Seattle ACO. Operators shall submit 
their requests through an appropriate FAA Principal Maintenance 
Inspector, who may add comments and then send it to the Manager, 
Seattle ACO.

    Note 2: Information concerning the existence of approved 
alternative methods of compliance with this AD, if any, may be 
obtained from the Seattle ACO.

    (d) 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.
    (e) This amendment becomes effective on June 18, 1997.
    Issued in Renton, Washington, on May 8, 1997.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 97-12682 Filed 5-13-97; 8:45 am]
BILLING CODE 4910-13-U