[Federal Register Volume 60, Number 241 (Friday, December 15, 1995)]
[Rules and Regulations]
[Pages 64317-64320]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 95-29302]
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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39
[Docket No. 95-NM-07-AD; Amendment 39-9445; AD 95-25-01]
Airworthiness Directives; Boeing Model 757 Series Airplanes
AGENCY: Federal Aviation Administration, DOT.
ACTION: Final rule.
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SUMMARY: This amendment supersedes 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 amendment requires
additional inspections, and replacement of certain parts, if necessary.
This amendment also provides for optional terminating action for
certain inspections. This amendment 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 AD are intended to
prevent broken power assist triggers, which could result in an
inoperative door opening system during an emergency evacuation.
DATES: Effective January 16, 1996. -
The incorporation by reference of certain publications listed in
the regulations is approved by the Director of the Federal Register as
of January 16, 1996.
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),
[[Page 64318]]
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: 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: A proposal to amend part 39 of the Federal
Aviation Regulations (14 CFR part 39) by superseding AD 91-07-09,
amendment 39-6951 (56 FR 12111, March 22, 1991), which is applicable to
certain Boeing Model 757 series airplanes, was published in the Federal
Register on April 3, 1995 (60 FR 16815). The action proposed to
continue to require various inspections and modifications of certain
mechanisms of the passenger doors, and replacement of certain parts, if
necessary. Additionally, that action proposed to require repetitive
inspections to detect worn, damaged, or cracked power assist triggers,
repair of worn triggers, and replacement, if necessary; repetitive
measurements of the clearance between the lockout cam and the crank
stop; and replacement of the lockout cams, if necessary. -
Interested persons have been afforded an opportunity to participate
in the making of this amendment. Due consideration has been given to
the comments received. -
Two commenters request that the FAA include a provision for
optional terminating action for the requirement to inspect the
emergency power assist triggers, as specified in paragraph (d) of the
proposal. One commenter states that repetitive actions should only be
necessary if there is significant evidence that doors inspected/
rectified in accordance with the alert service bulletin deteriorate
with time. This commenter points out that paragraph I.D. of the alert
service bulletin (that is referenced in the proposal as the appropriate
source of service information) indicates that once the door is rigged
correctly, the inspections can be discontinued. A second commenter
states that Boeing has indicated that modification of the subject
lockout mechanism would terminate the proposed repetitive inspections.
-
The FAA does not concur. Although the Boeing alert service bulletin
would allow termination of the repetitive inspections of the power
assist trigger if the lockout cam is within specified measurements, the
FAA finds that the requirement to repetitively inspect the emergency
power assist triggers, as required by paragraph (d) of the final rule
cannot be terminated. Failure of the lockout cam is not the only
possible failure mode that could result in failure of the emergency
power assist trigger, e.g., the power assist trigger function could
fail in the event of a door mis-sequencing while being opened. -
Two commenters request that the FAA include a provision for
optional terminating action for the requirement to repetitively measure
the clearance between the lockout cam and the crank stop, as specified
in paragraph (e), of the proposal. One of the commenters, Boeing,
clarifies that the intent of the alert service bulletin is to specify
that no further action is necessary if the clearance between the
lockout cam and crank stop is within specified limits and the emergency
power assist trigger is not damaged or cracked. Boeing indicates that a
phrase stating that ``if the clearance is within limits, no more work
is necessary'' was omitted inadvertently from paragraph I.D. of the
alert service bulletin. Boeing adds that no further incidents of
failure of the emergency power assist triggers have been reported.
Therefore, Boeing recommends that the FAA revise paragraphs (e)(1) and
(e)(2) of the final rule accordingly. -
The FAA concurs with the commenters' requests. The FAA has
determined that measurement of the clearance between the lockout cam
and the crank stop need not be accomplished on a repetitive basis. The
FAA has revised paragraph (e) of the final rule to remove the
requirement to measure repetitively. -
Two commenters request that the actions specified in Boeing Telex
M-7272-94-6665, ``New Redesigned Girt Bar Mechanism and Emergency Power
Assist (EPA) System,'' be considered terminating action for the
proposed repetitive inspections. The commenters do not justify this
request. The FAA does not concur with the commenters' request. The FAA
has confirmed with Boeing that the telex referenced by the commenters
is an explanation of proposed design changes that may possibly be made
in the future. However, these changes could constitute a major redesign
to the escape system and may not be offered as a solution for in-
service airplanes. The FAA has determined that, since an unsafe
condition exists, the inspections must be conducted to ensure continued
safety. Furthermore, the FAA does not consider it appropriate to delay
this rulemaking action until such time that these design changes are
approved and available.
Three commenters request that, if repetitive inspections will be
required, the FAA extend the repetitive inspection intervals to
coincide with regularly scheduled ``C'' checks (i.e., from the proposed
6 months to 8 months). The FAA does not concur with the commenters'
request to extend the compliance time. In developing an appropriate
compliance time for this action, the FAA considered the safety
implications and the practical aspect of performing the required
inspections within an interval of time that parallels normal scheduled
maintenance for the majority of affected operators. In consideration of
these items, as well as the reports of broken power assist triggers,
the FAA has determined that 6 months represents the maximum interval of
time allowable wherein the inspections can reasonably be accomplished
and an acceptable level of safety can be maintained. However, paragraph
(f) of the final rule does provide affected operators the opportunity
to apply for an adjustment of the compliance time if data are presented
to justify such an adjustment. -
The FAA has revised the economic impact information, below, to
include cost estimates for accomplishment of the actions required
currently by AD 91-07-09. -
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. -
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 will be
affected by this AD. -
The actions that are currently required by AD 91-07-09 take
approximately 51 work hours per airplane to accomplish, at an average
labor rate of $60 per work hour. Based on these figures, the cost
impact on U.S. operators of the actions currently required by AD 91-07-
09 is estimated to be $988,380, or $3,060 per airplane. -
The new actions that are required by this new AD will take
approximately 12 work hours (2 work hours per passenger door) per
airplane to accomplish, at an average labor rate of $60 per work hour.
Based on these figures, the cost impact on U.S. operators of the new
requirements of this AD is estimated to
[[Page 64319]]
be $232,560, or $720 per airplane ($120 per door), per inspection
cycle. -
Should an operator be required to accomplish the replacement of
power assist triggers, it will take approximately 18 work hours per
airplane (3 work hours per passenger door) to accomplish the
replacement, at an average labor rate of $60 per work hour. Required
parts will cost approximately $1,800 per airplane ($300 per passenger
door). Based on these figures, the cost impact of the replacement
action is estimated to be $2,880 per airplane ($480 per passenger
door). -
The cost impact figures discussed above are 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 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 removing amendment 39-6951 (56 FR
12111, March 22, 1991), and by adding a new airworthiness directive
(AD), amendment 39-9445, to read as follows:
95-25-01 Boeing: Amendment 39-9445. 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) of this AD 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 inspection 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 inspection 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, no
further action is required by this paragraph. -
(2) If the clearance between the lockout cam and the crank stop
is beyond the limits
[[Page 64320]]
specified in the alert service bulletin, prior to further flight,
accomplish the actions specified by either paragraph (e)(2)(i) or
(e)(2)(ii) of this AD. -
(i) Adjust the lockout cam until the correct clearance is
obtained, in accordance with the alert service bulletin. Or -
(ii) If the 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
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 actions shall be done in accordance with 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. 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 or at the Office of the
Federal Register, 800 North Capitol Street, NW., suite 700,
Washington, DC. -
(i) This amendment becomes effective on January 16, 1996.
Issued in Renton, Washington, on November 27, 1995.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification
Service.
[FR Doc. 95-29302 Filed 12-14-95; 8:45 am]
BILLING CODE 4910-13-U]