[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
