[Federal Register Volume 59, Number 43 (Friday, March 4, 1994)]
[Unknown Section]
[Page 0]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 94-4953]


[[Page Unknown]]

[Federal Register: March 4, 1994]


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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 94-NM-07-AD]

 

Airworthiness Directives; Boeing Model 747-400 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the adoption of a new airworthiness 
directive (AD) that is applicable to all Boeing Model 747-400 series 
airplanes. This proposal would require various inspections and 
functional tests of the thrust reverser control and indication system, 
and correction of any discrepancy found. This proposal is prompted by 
an investigation to determine the controllability of Model 747 series 
airplanes following an in-flight thrust reverser deployment, which has 
revealed that, in the event of thrust reverser deployment during high-
speed climb or during cruise, these airplanes could experience control 
problems. The actions specified by the proposed AD are intended to 
ensure the integrity of the fail safe features of the thrust reverser 
system by preventing possible failure modes in the thrust reverser 
control system that can result in inadvertent deployment of a thrust 
reverser during flight.

DATES: Comments must be received by April 29, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 94-NM-07-AD, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9 a.m. and 3 p.m., Monday through Friday, except Federal 
holidays.
    The service information referenced in the proposed rule may be 
obtained from Boeing Commercial Airplane Group, P.O. Box 3707, Seattle, 
Washington 98124-2207. This information may be examined at the FAA, 
Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, 
Washington.

FOR FURTHER INFORMATION CONTACT: Jon Regimbal, Aerospace Engineer, 
Propulsion Branch, ANM-140S, FAA, Transport Airplane Directorate, 
Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2687; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION:

Comments Invited

    Interested persons are invited to participate in the making of the 
proposed rule by submitting such written data, views, or arguments as 
they may desire. Communications shall identify the Rules Docket number 
and be submitted in triplicate to the address specified above. All 
communications received on or before the closing date for comments, 
specified above, will be considered before taking action on the 
proposed rule. The proposals contained in this notice may be changed in 
light of the comments received.
    Comments are specifically invited on the overall regulatory, 
economic, environmental, and energy aspects of the proposed rule. All 
comments submitted will be available, both before and after the closing 
date for comments, in the Rules Docket for examination by interested 
persons. A report summarizing each FAA-public contact concerned with 
the substance of this proposal will be filed in the Rules Docket.
    Commenters wishing the FAA to acknowledge receipt of their comments 
submitted in response to this notice must submit a self-addressed, 
stamped postcard on which the following statement is made: ``Comments 
to Docket Number 94-NM-07-AD.'' The postcard will be date stamped and 
returned to the commenter.

Availability of NPRMs

    Any person may obtain a copy of this NPRM by submitting a request 
to the FAA, Transport Airplane Directorate, ANM-103, Attention: Rules 
Docket No. 94-NM-07-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    In May 1991, a Boeing Model 767 series airplane was involved in an 
accident in which a thrust reverser deployed inadvertently during 
flight. While the investigation of the accident has not revealed the 
cause of that deployment, it has identified a number of possible 
failure modes in the thrust reverser control system. Inadvertent 
deployment of a thrust reverser during flight could result in reduced 
controllability of the airplane.
    The FAA and the aviation industry are conducting an in-depth 
investigation of the thrust reverser systems installed on various types 
of large transport airplanes. In particular, this investigation has 
focused on airplane controllability in the event of an in-flight 
deployment of a thrust reverser, and thrust reverser reliability in 
general. Based on the data gathered from this ongoing investigation, 
the FAA has issued several airworthiness directives (AD) to require 
periodic inspections and tests of the thrust reverser systems on 
certain Boeing Model 757 and 767 series airplanes [for example, 
reference AD 91-20-09, Amendment 39-8043 (56 FR 46725, September 16, 
1991) for certain Model 757 series airplanes; and AD 92-24-03, 
Amendment 39-8408 (57 FR 53258, November 9, 1992) for certain Model 767 
series airplanes]. In addition, the FAA has issued or proposed several 
AD's to require an additional locking device on thrust reversers that 
are installed on Model 737-300/-400/-500, 757, and 767 series 
airplanes. This action was taken to enhance the level of reliability on 
airplane models that were determined to have unacceptable flight 
characteristics following an in-flight deployment of a thrust reverser. 
-
    Until now, the investigation of thrust reverser system reliability 
on Boeing Model 747 series airplanes has not been given as high a 
priority as the other Boeing models because Model 747 series airplanes 
have never experienced control problems as a result of an in-flight 
thrust reverser deployment. In fact, previously there had been at least 
29 incidents in which the thrust reverser installed on Model 747 series 
airplanes powered by Pratt & Whitney JT9D series engines deployed 
during flight and the airplane was still controllable. Based on this 
long safety record and the available evidence up to this time, it has 
been accepted generally that all Model 747 series airplanes would be 
shown to be controllable throughout the flight envelope following an 
in-flight thrust reverser deployment. -
    Recently, however, Boeing has responded to an FAA request for 
further investigation to determine the controllability of Model 747 
series airplanes following an in-flight thrust reverser deployment. The 
investigation results thus far indicate that Model 747-400 series 
airplanes could experience certain control problems in the event of a 
thrust reverser deployment occurring during high speed climb or during 
cruise.
    In light of this new information, the FAA has determined that 
certain inspections and functional tests of the thrust reverser control 
and indication system on Model 747-400 series airplanes, similar to 
those required previously for Model 757 and 767 series airplanes, are 
necessary as precautionary actions to provide an acceptable level of 
safety for Model 747-400 series airplanes. Accomplishment of these 
inspections and functional tests is intended to reduce the exposure of 
the airplane to potential undetected single failures in the thrust 
reverser control system. The presence of an undetected failure in the 
thrust reverser control system, in some cases, can increase the 
likelihood of an uncommanded thrust reverser deployment in the event of 
an additional thrust reverser control system failure.
    The assessment of the thrust reverser system reliability of Model 
747-100, -200, -300, SP, and SR series airplanes is continuing. The FAA 
may consider rulemaking action for those airplanes based upon the 
results of that assessment.
    The FAA has reviewed and approved Boeing Service Bulletins 747-78-
2112, dated November 11, 1993 (for Model 747-400 series airplanes 
powered by Pratt & Whitney PW4000 series engines); 747-78-2113, dated 
November 11, 1993 (for Model 747-400 series airplanes powered by 
General Electric CF6-80C2 series engines); and 747-78-2115, dated 
October 28, 1993 (for Model 747-400 series airplanes powered by Rolls-
Royce RB211-524G/H series engines). These service bulletins describe 
procedures for various inspections and functional tests of the thrust 
reverser control and indication system, and correction of any 
discrepancy found.
    Since an unsafe condition has been identified that is likely to 
exist or develop on other products of this same type design, the 
proposed AD would require various inspections and functional tests of 
the thrust reverser control and indication system, and correction of 
any discrepancy found. The actions would be required to be accomplished 
in accordance with the service bulletins described previously.
    This proposed AD also would require that operators submit a report 
of initial inspection and test results to the FAA.
    This is considered to be interim action until final action is 
identified for these airplanes, at which time the FAA may consider 
further rulemaking.
    There are approximately 286 Model 747-400 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 39 Model 
747-400 series airplanes powered by Pratt & Whitney PW4000 series 
engines of U.S. registry would be affected by this proposed AD, that it 
would take approximately 48 work hours per airplane to accomplish the 
proposed actions, and that the average labor rate is $55 per work hour. 
Based on these figures, the total cost impact of the proposed AD on 
U.S. operators of Model 747-400 series airplanes powered by Pratt & 
Whitney PW4000 series engines is estimated to be $102,960, or $2,640 
per airplane.
    The total cost impact figure discussed above is based on 
assumptions that no operator has yet accomplished any of the proposed 
requirements of this AD action, and that no operator would accomplish 
those actions in the future if this AD were not adopted.
    Currently, there are no Model 747-400 series airplanes powered by 
General Electric CF6-80C2 series engines on the U.S. Register. However, 
should one of these airplanes be imported and placed on the U.S. 
Register in the future, it would require approximately 60 work hours to 
accomplish the proposed actions, at an average labor charge of $55 per 
work hour. Based on these figures, the total cost impact of this AD 
would be $3,300 per airplane.
    Additionally, there are no Model 747-400 series airplanes powered 
by Rolls-Royce RB211-524G/H series engines on the U.S. Register at this 
time. However, should one of these airplanes be imported and placed on 
the U.S. Register in the future, it would require approximately 30 
hours to accomplish the proposed actions, at an average labor charge of 
$55 per work hour. Based on these figures, the total cost impact of 
this AD would be $1,650 per airplane.
    The regulations proposed herein would 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 
proposal would not have sufficient federalism implications to warrant 
the preparation of a Federalism Assessment.
    For the reasons discussed above, I certify that this proposed 
regulation (1) is not a ``significant regulatory action'' under 
Executive Order 12866; (2) is not a ``significant rule'' under the DOT 
Regulatory Policies and Procedures (44 FR 11034, February 26, 1979); 
and (3) if promulgated, 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 copy of the draft 
regulatory evaluation prepared for this action is contained in the 
Rules Docket. A copy of it may be obtained by contacting 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.

The Proposed Amendment

    Accordingly, pursuant to the authority delegated to me by the 
Administrator, the Federal Aviation Administration proposes to amend 14 
CFR part 39 of the Federal Aviation Regulations 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:

Boeing: Docket 94-NM-07-AD.

    Applicability: All Model 747-400 series airplanes, certificated 
in any category.
    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure the integrity of the fail safe features of the thrust 
reverser system, accomplish the following:
    (a) For Model 747-400 series airplanes powered by Pratt & 
Whitney PW4000 series engines: Accomplish paragraphs (a)(1) and 
(a)(2) of this AD in accordance with Boeing Service Bulletin 747-78-
2112, dated November 11, 1993. -
    (1) Within 90 days after the effective date of this AD, perform 
an inspection to detect damage to the bullnose seal on the 
translating sleeve of the thrust reverser in accordance with 
paragraph C. of the Accomplishment Instructions of the service 
bulletin; and perform a test of the lock mechanism of the center 
locking actuator in accordance with paragraph E. of the 
Accomplishment Instructions of the service bulletin. Repeat this 
inspection and test thereafter at intervals not to exceed 1,000 
hours time-in-service.
    (2) Within 6 months after the effective date of this AD, perform 
inspections and functional tests of the thrust reverser control and 
indication systems in accordance with paragraphs A., B., D., and F. 
through M. of the Accomplishment Instructions of the Service 
Bulletin. Repeat these inspections and functional tests thereafter 
at intervals not to exceed 15 months.
    (b) For Model 747-400 series airplanes powered by General 
Electric CF6-80C2 series engines: Accomplish paragraphs (b)(1) and 
(b)(2) of this AD in accordance with Boeing Service Bulletin 747-78-
2113, dated November 11, 1993.
    (1) Within 90 days after the effective date of this AD, perform 
an inspection to detect damage to the bullnose seal on the 
translating sleeve of the thrust reverser in accordance with 
paragraph B. of the Accomplishment Instructions of the service 
bulletin; and perform a continuity test of the position switch 
module of the center drive unit (CDU) and a cone brake test of the 
CDU in accordance with paragraph C. of the Accomplishment 
Instructions of the service bulletin. Repeat the inspection and 
tests thereafter at intervals not to exceed 1,000 hours time-in-
service.
    (2) Within 6 months after the effective date of this AD, perform 
inspections and functional tests of the thrust reverser control and 
indication systems in accordance with paragraphs A., D., F., G., H., 
and J. through M. of the Accomplishment Instructions of the Service 
Bulletin. Repeat these inspections and functional tests thereafter 
at intervals not to exceed 15 months.
    (c) For Model 747-400 series airplanes powered by Rolls-Royce 
RB211-524G/H series engines: Within 6 months after the effective 
date of this AD, and thereafter at intervals not to exceed 15 
months, perform inspections and functional tests of the thrust 
reverser control and indication systems in accordance with 
paragraphs D. through K. of the Accomplishment Instructions of 
Boeing Service Bulletin 747-78-2115, dated October 28, 1993.
    (d) If any of the inspections and/or functional tests required 
by this AD cannot be successfully performed, or if any discrepancy 
is found during those inspections and/or functional tests, prior to 
further flight, correct the discrepancy found, in accordance with 
Boeing Service Bulletin 747-78-2112, dated November 11, 1993 (for 
Model 747-400 series airplanes powered by Pratt & Whitney PW4000 
series engines); 747-78-2113, dated November 11, 1993 (for Model 
747-400 series airplanes powered by General Electric CF6-80C2 series 
engines); or 747-78-2115, dated October 28, 1993 (for Model 747-400 
series airplanes powered by Rolls-Royce RB211-524G/H series 
engines); as applicable.
    (e) Within 10 days after performing each initial inspection and 
test required by this AD, submit a report of the inspection and/or 
test results, both positive and negative, to the FAA, Seattle 
Aircraft Certification Office (ACO), ANM-100S, 1601 Lind Avenue, 
SW., Renton, Washington 98055-4056; fax (206) 227-1181. Information 
collection requirements contained in this regulation have been 
approved by the Office of Management and Budget (OMB) under the 
provisions of the Paperwork Reduction Act of 1980 (44 U.S.C. 3501 et 
seq.) and have been assigned OMB Control Number 2120-0056.
    (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, Seattle 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, Seattle ACO.

    Note: 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 
Federal Aviation Regulations (FAR) 21.197 and 21.199 to operate the 
airplane to a location where the requirements of this AD can be 
accomplished.

    Issued in Renton, Washington, on February 28, 1994.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 94-4953 Filed 3-3-94; 8:45 am]
BILLING CODE 4910-13-U