[Federal Register Volume 60, Number 63 (Monday, April 3, 1995)]
[Proposed Rules]
[Pages 16814-16817]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-8079]



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[[Page 16815]]


DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 95-NM-07-AD]


Airworthiness Directives; Boeing Model 757 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.


ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes the supersedure of an existing 
airworthiness directive (AD), applicable to certain Boeing Model 757 
series airplanes, that currently requires various modifications and 
terminating actions for the passenger door, and repair, if necessary. 
This action would require additional inspections, and replacement of 
certain parts, if necessary. This proposal is prompted by reports of 
excessive gaps between lockout cams and crank stops, which resulted in 
broken power assist triggers. The actions specified by this proposed AD 
are intended to prevent broken power assist triggers, which could 
result in an inoperative door opening system during an emergency 
evacuation.

DATES: Comments must be received by May 31, 1995.


ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-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: Roy Boffo, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle 
Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, 
Washington 98055-4056; telephone (206) 227-2780; 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 95-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. 95-NM-07-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion

    On March 13, 1991, the FAA issued AD 91-07-09, amendment 39-6951 
(56 FR 12111, March 22, 1991), applicable to certain Boeing Model 757 
series airplanes, which requires various modifications and terminating 
actions for the passenger door, and repair, if necessary. That action 
was prompted by reports of fractured emergency power assist triggers. 
The requirements of that AD are intended to prevent an inoperative 
emergency power assist door opening system during an emergency 
evacuation.
    Since the issuance of that AD, the FAA has received additional 
reports of broken power assist triggers. One broken power assist 
trigger was found on a door before the airplane was delivered to the 
operator. The FAA also has received reports of excessive gaps between 
lockout cams and crank stops. Investigation has revealed that when the 
crank stop is in the arm/engage position, excessive fore and aft 
clearance between the lockout cam and the crank stop can result in 
broken power assist triggers. This condition, if not detected and 
corrected, could result in an inoperative power assist system of the 
passenger door during an emergency evacuation.
    Based on these findings, the FAA has determined that the distance 
between the lockout cam and the crank stop must be measured to ensure 
that gaps are not excessive. In addition, the FAA finds that 
inspections must be performed to detect damaged or cracked power assist 
triggers that may prevent the door opening systems from operating.
    The FAA has reviewed and approved Boeing Alert Service Bulletin 
757-52A0023, Revision 3, dated November 18, 1993, which describes 
procedures for repetitive inspections to detect worn, damaged, or 
cracked power assist triggers, repair of worn fittings, and replacement 
of any discrepant trigger. The alert service bulletin also describes 
procedures for repetitive measurement of the clearance between the 
lockout cam and the crank stop, and replacement of the lockout cam, if 
necessary.
    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 supersede AD 91-07-09 to continue to require various 
inspections and modifications of certain mechanisms of the passenger 
doors, and replacement of certain parts, if necessary. This AD would 
require repetitive inspections to detect worn, damaged, or cracked 
power assist triggers, repair of worn triggers, and replacement, if 
necessary. This AD will also require repetitive measurements of the 
clearance between the lockout cam and the crank stop; and replacement 
of the lockout cams, if necessary. These actions would be required to 
be accomplished in accordance with the alert service bulletin described 
previously.
    There are approximately 578 Model 757 series airplanes of the 
affected design in the worldwide fleet. The FAA estimates that 323 
airplanes (6 passenger doors per airplane) of U.S. registry would be 
affected by this proposed AD, that it would take approximately 12 work 
hours (2 work hours per door) to accomplish the proposed actions, and 
that the average labor rate is $60 per work hour. Based on these 
figures, the total cost impact of the proposed AD on U.S. operators is 
estimated to be $232,560, or $720 per airplane ($120 per door), per 
inspection cycle.
    Should an operator be required to accomplish the necessary 
replacement of power assist triggers, it would take approximately 18 
work hours per [[Page 16816]] airplane (3 work hours per passenger 
door) to accomplish the replacement, at an average labor rate of $60 
per work hour. Required parts would cost approximately $1,800 per 
airplane ($300 per passenger door). Based on these figures, the total 
cost impact of any necessary replacement action is estimated to be 
$2,880 per airplane ($480 per passenger door).
    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.
    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 
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 removing amendment 39-6951 (56 FR 
12111, March 22, 1991), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 95-NM-07-AD. Supersedes AD 91-07-09, Amendment 39-
6951.

    Applicability: Model 757 series airplanes, as listed in any of 
the following service bulletins: Boeing Service Bulletin 757-52-0042 
dated March 30, 1989, Boeing Service Bulletin 757-52-0042, Revision 
1, dated April 26, 1990; and Boeing Alert Service Bulletin 757-
52A0023, Revision 3, dated November 18, 1993; certificated in any 
category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
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 use the authority 
provided in paragraph (f) to request approval from the FAA. This 
approval may address either no action, if the current configuration 
eliminates the unsafe condition; or different actions necessary to 
address the unsafe condition described in this AD. Such a request 
should include an assessment of the effect of the changed 
configuration on the unsafe condition addressed by this AD. In no 
case does the presence of any modification, alteration, or repair 
remove any airplane from the applicability of this AD.

    Compliance: Required as indicated, unless accomplished 
previously.
    To ensure proper operation of the door opening system during an 
emergency evacuation, accomplish the following:
    (a) For airplanes identified as Group 1 in Boeing Service 
Bulletin 757-52-0042, dated March 30, 1989, and Revision 1, dated 
April 26, 1990: Within 350 flight hours after January 6, 1990 (the 
effective date of AD 89-25-09, amendment 39-6407), accomplish 
paragraphs (a)(1), (a)(2), and (a)(3) of this AD, in accordance with 
either service bulletin. Any interference or improper clearance 
detected during any inspections required by this paragraph must be 
repaired prior to further flight, in accordance with either service 
bulletin.
    (1) Modify the forward right-hand passenger door.
    (2) Inspect all passenger doors for evidence of interference 
between the trigger support housing and the upper hinge arm.
    (3) Inspect all passenger doors for proper clearance between the 
power assist trigger and the door and fuselage skin.
    (b) For all airplanes identified in Boeing Service Bulletin 757-
52-0042, dated March 30, 1989, and Revision 1, dated April 26, 1990: 
Within 350 flight hours after January 6, 1990 (the effective date of 
AD 89-25-09, amendment 39-6407), and thereafter at intervals not to 
exceed 6 months, accomplish paragraphs (b)(1), (b)(2), (b)(3), and 
(b)(4) of this AD, in accordance with either service bulletin. Any 
damage, improper adjustment, or improper operation detected during 
any of the inspections required by this paragraph must be repaired 
prior to further flight, in accordance with either service bulletin.
    (1) Inspect the forward doors for proper adjustment of the 
lockout mechanism of the door emergency power assist system.
    (2) Inspect all passenger door emergency power assist triggers 
for wear marks, damage, or fracture.
    (3) Inspect trigger spring cylinders for proper operation.
    (4) Inspect roller arms for damage.
    (c) For all airplanes identified in Boeing Service Bulletin 757-
52-0042, Revision 1, dated April 26, 1990: Within 18 months after 
April 29, 1991 (the effective date of AD 91-07-09, amendment 39-
6951), accomplish paragraphs (c)(1), (c)(2), (c)(3), and (c)(4) of 
this AD, in accordance with Section III, Part III, of the service 
bulletin. Any damage, defect, improper adjustment, or improper 
operation detected during any inspection required by this paragraph 
must be repaired, prior to further flight, in accordance with the 
service bulletin. Accomplishment of the actions required by this 
paragraph constitutes terminating action for the periodic 
inspections required by paragraph (b) of this AD.
    (1) On forward doors, install the lockout link and inspect the 
lockout mechanism for proper adjustment.
    (2) On all passenger doors, install the new trigger guard. and 
inspect the emergency power assist triggers for wear marks, damage, 
or fracture.
    (3) On all passenger doors, modify the trigger spring cylinder 
end cap and inspect the spring cylinder for proper operation.
    (4) On all passenger doors, inspect roller arms for damage.
    (d) For all airplanes identified in Boeing Alert Service 
Bulletin 757-52A0023, Revision 3, dated November 18, 1993: Within 6 
months after the effective date of this AD, perform an inspection to 
detect wear marks, damage, or cracking on the upper surface of the 
emergency power assist triggers at all passenger doors, in 
accordance with the alert service bulletin. Repeat the inspection 
thereafter at intervals not to exceed 6 months.
    (1) If any wear mark is detected, prior to further flight, 
repair in accordance with the alert service bulletin.
    (2) If any damage or cracking is detected, prior to further 
flight, replace the power assist triggers, in accordance with the 
alert service bulletin.
    (e) For all airplanes identified in Boeing Alert Service 
Bulletin 757-52A0023, Revision 3, dated November 18, 1993: Within 6 
months after the effective date of this AD, measure the clearance 
between the lockout cam and the crank stop, in accordance with the 
alert service bulletin.
    (1) If the clearance between the lockout cam and the crank stop 
is within the limits specified in the alert service bulletin, 
thereafter, repeat the measurement at intervals not to exceed 6 
months.
    (2) If the clearance between the lockout cam and the crank stop 
is beyond the limits specified in the alert service bulletin, prior 
to further flight, accomplish either paragraph (e)(2)(i) or 
(e)(2)(ii) of this AD. Thereafter, [[Page 16817]] repeat the 
measurement at intervals not to exceed 6 months.
    (i) Adjust the lockout cam until the correct clearance is 
obtained, in accordance with the alert service bulletin, Or
    (ii) If correct clearance cannot be obtained by adjusting the 
lockout cam, replace the lockout cam, in accordance with the alert 
service bulletin.
    (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 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, 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.

    (g) Special flight permits may be issued in accordance with 
Secs. 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.

    Issued in Renton, Washington, on March 27, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 95-8079 Filed 3-31-95; 8:45 am]
BILLING CODE 4910-13-U