[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]