[Federal Register Volume 61, Number 63 (Monday, April 1, 1996)]
[Proposed Rules]
[Pages 14269-14271]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-7856]



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DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

14 CFR Part 39

[Docket No. 95-NM-222-AD]


Airworthiness Directives; Boeing Model 727 Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Notice of proposed rulemaking (NPRM).

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SUMMARY: This document proposes to revise an existing airworthiness 
directive (AD), applicable to all Boeing Model 727 series airplanes, 
that currently requires inspections to detect loose attach fitting 
bolts of the door actuator of the main landing gear (MLG), inspections 
to determine whether serrations are fully mated, and various follow-on 
corrective actions. That AD also provides for an optional terminating 
modification for certain requirements. That AD was prompted by reports 
of loose attach fitting bolts of the door actuator of the MLG. The 
actions specified by that AD are intended to prevent an airplane from 
landing with one MLG partially extended. This action would provide 
operators the option of terminating all of the requirements of that AD 
by replacing the aluminum rib fitting with a new steel rib fitting, or 
by modifying the rib fitting assembly and performing various follow-on 
actions.

DATES: Comments must be received by May 9, 1996.

ADDRESSES: Submit comments in triplicate to the Federal Aviation 
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-222-AD, 1601 Lind Avenue SW., Renton, 
Washington 98055-4056. Comments may be inspected at this location 
between 9:00 a.m. and 3:00 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: Walter Sippel, Aerospace Engineer, 
Airframe Branch, ANM-120S, FAA, Seattle Aircraft Certification Office, 
1601 Lind Avenue SW., Renton, Washington; telephone (206) 227-2774; 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

[[Page 14270]]
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-222-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-222-AD, 1601 Lind Avenue SW., Renton, Washington 
98055-4056.

Discussion

    On January 11, 1993, the FAA issued AD 93-01-14, amendment 39-8468 
(58 FR 5574, January 22, 1993), applicable to all Boeing Model 727 
series airplanes, to require inspections to detect loose attach fitting 
bolts of the door actuator of the main landing gear (MLG), inspections 
to determine whether serrations are fully mated, and various follow-on 
corrective actions. That action also provides for the termination of 
certain inspection requirements. That action was prompted by reports of 
loose attach fitting bolts of the door actuator of the MLG. The 
requirements of that AD are intended to prevent an airplane from 
landing with one MLG partially extended.
    Additionally, on December 15, 1989, the FAA issued AD 90-02-19, 
amendment 39-6433 (55 FR 601, January 8, 1990), to require inspections 
of all Model 727 series airplanes to detect cracking of the actuator 
rib fitting of the inboard door of the MLG, and rework or replacement 
of any cracked fitting. That action was prompted by an incident in 
which the actuator rib fitting of the MLG door on a Model 727 series 
airplane fractured and, consequently, the left MLG of the airplane 
failed to extend for landing. The requirements of that AD are intended 
to prevent damage to the airplane caused by a failure of the landing 
gear to extend due to a fractured rib fitting.
    Since the issuance of those AD's, the FAA has reviewed and approved 
Boeing Alert Service Bulletin 727-32A0399, dated July 13, 1995. The 
alert service bulletin describes procedures for:
    1. Either a high frequency eddy current or dye penetrant inspection 
to detect cracking of the actuator rib fitting of the MLG.
    2. Modification of the rib fitting assembly, which includes 
changing the existing 0.250-inch radius to a 0.42-inch radius, and 
repetitive high frequency eddy current or dye penetrant inspections, 
for findings of no cracking. The modification also includes installing 
new shims, nuts, bolts, lockwires, and cotter pins, as well as 
establishing new torque requirements. (These actions are specified in 
Figure 4 of the alert service bulletin.) Accomplishment of this 
modification and the follow-on actions would eliminate the need for all 
of the inspections required by AD 93-01-14.
    3. Replacement of the currently installed aluminum rib fitting with 
a new steel rib fitting, for findings of cracking. (This action is 
specified in Figure 5 of the alert service bulletin.) Such replacement 
would eliminate the need for all of the inspections required by AD 93-
01-14.
    The FAA is currently proposing, in a separate rulemaking action 
(Docket No. 95-NM-223-AD), to mandate the inspections specified in Item 
1., above, and the modification of the rib fitting assembly, specified 
in Item 2., above. Accomplishment of either of these actions would 
terminate the requirements of AD 93-01-14.
    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 revise AD 93-01-14 to continue to require inspections 
of the attach fitting bolts of the door actuator of the MLG, 
inspections to determine whether serrations are fully mated, and 
various follow-on corrective actions.
    This proposed AD would provide operators the option of terminating 
all of the inspections required by AD 93-01-14 by either replacing the 
currently installed aluminum rib fitting with a new steel rib fitting, 
or modifying the rib fitting assembly and accomplishing the follow-on 
actions. Such replacement or modification would also terminate the 
inspections required by AD 90-02-19. If accomplished, the replacement, 
or modification and follow-on actions, would be required to be 
performed in accordance with the alert service bulletin described 
previously.
    The FAA is not proposing to mandate replacement of the currently 
installed aluminum rib fitting, or modification of the rib fitting 
assembly and follow-on actions, because the inspections required by AD 
93-01-14 have consistently detected, prior to catastrophic 
consequences, loose attach fitting bolts of the door actuator of the 
MLG and serrations that are not fully mated. Service history has 
demonstrated that these inspections have ensured safety of the fleet 
adequately for a number of years.
    There are approximately 1,631 Boeing Model 727 series airplanes of 
the affected design in the worldwide fleet. The FAA estimates that 
1,166 airplanes of U.S. registry would be affected by this proposed AD.
    The inspections currently required by AD 93-01-14 take 
approximately 1 work hour per airplane to accomplish, at an average 
labor rate of $60 per work hour. Based on these figures, the cost 
impact of the proposed AD on U.S. operators is estimated to be $69,960, 
or $60 per airplane, per inspection cycle.
    Should an operator elect to accomplish the optional terminating 
action by replacing the currently installed aluminum rib fitting with a 
new steel rib fitting, it would take approximately 4 work hours per 
airplane at an average labor rate of $60 per work hour. Required parts 
would cost approximately $428 per airplane. Based on these figures, the 
cost impact of this proposed optional terminating action on U.S. 
operators is estimated to be $668 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 
part 39 of the Federal Aviation Regulations (14 CFR part 39) as 
follows:

[[Page 14271]]


PART 39--AIRWORTHINESS DIRECTIVES

    1. The authority citation for part 39 continues to read as follows:

    Authority: 49 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended]

    2. Section 39.13 is amended by removing amendment 39-8468 (58 FR 
5574, January 22, 1993), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 95-NM-222-AD. Revises AD 93-01-14, Amendment 39-8468.

    Applicability: All Model 727 airplanes, certificated in any 
category.

    Note 1: This AD applies to each airplane identified in the 
preceding applicability provision, regardless of whether it has been 
otherwise 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 request approval for an 
alternative method of compliance in accordance with paragraph (j) of 
this AD. The request should include an assessment of the effect of 
the modification, alteration, or repair on the unsafe condition 
addressed by this AD; and, if the unsafe condition has not been 
eliminated, the request should include specific proposed actions to 
address it.

    Compliance: Required as indicated, unless accomplished 
previously.
    To prevent an airplane from landing with one main landing gear 
(MLG) partially extended due to loose attach fitting bolts, 
accomplish the following:
    (a) Within the next 1,500 flight cycles after October 15, 1991 
(the effective date of AD 91-15-14, amendment 39-7078), inspect to 
detect loose attach fitting bolts of the door actuator of the MLG in 
accordance with paragraph III., Accomplishment Instructions, of 
Boeing Service Bulletin 727-32-0383, dated December 6, 1990.
    (b) If any loose bolt is detected during the inspection required 
by paragraph (a) of this AD, prior to further flight, accomplish 
either Figure 1 or 2 of Boeing Service Bulletin 727-32-0383, dated 
December 6, 1990.
    (c) For airplanes that have accomplished the actions required by 
paragraph (a) of this AD prior to February 23, 1993 (the effective 
date of AD 93-01-14, amendment 39-8468): Prior to the accumulation 
of 3,700 flight cycles after accomplishing the inspection or 
replacement required by paragraphs (a) and (b) of this AD, or within 
3 years after February 23, 1993, whichever occurs earlier, inspect 
to ensure that serrations of the attach fitting of the door actuator 
of the MLG are fully mated, and to detect loose attach fitting bolts 
of the door actuator of the MLG; in accordance with paragraph III., 
Accomplishment Instructions, of Boeing Service Bulletin 727-32-0383, 
Revision 1, dated January 30, 1992. Repeat this inspection 
thereafter at intervals not to exceed 3,700 flight cycles or 3 years 
after the immediately preceding inspection, whichever occurs 
earlier.
    (d) If serrations are not fully mated, or if any loose bolt is 
detected during the inspections required by paragraph (c) of this 
AD, prior to further flight, accomplish either Figure 1 or Figure 2 
of Boeing Service Bulletin 727-32-0383, dated December 6, 1990; or 
Revision 1, dated January 30, 1992.
    (1) If Figure 1 of either service bulletin is accomplished, 
repeat the inspection required by paragraph (c) of this AD at 
intervals not to exceed 3,700 flight cycles or 3 years after the 
immediately preceding inspection, whichever occurs earlier.
    (2) Accomplishment of Figure 2 of Revision 1 of the service 
bulletin (for all bolts); or accomplishment of Figure 2 of the 
service bulletin dated December 6, 1990 (for bolts 1 and 2) and 
accomplishment of a torque check of bolt 3 in accordance with 
Revision 1 of the service bulletin; constitutes terminating action 
for the inspection requirements of paragraph (c) of this AD.
    (e) For airplanes on which the inspections required by paragraph 
(a) of this AD prior to February 23, 1993 (the effective date of AD 
93-01-14, amendment 39-8468) have not previously accomplished the 
actions: Prior to the accumulation of 1,500 flight cycles after 
February 23, 1993, or within 18 months after February 23, 1993, 
whichever occurs earlier, inspect to ensure that serrations of the 
attach fitting bolts of the door actuator of the MLG are fully 
mated, and to detect loose attach fitting bolts; in accordance with 
paragraph III., Accomplishment Instructions, of Boeing Service 
Bulletin 727-32-0383, Revision 1, dated January 30, 1992. Repeat 
this inspection thereafter at intervals not to exceed 3,700 flight 
cycles or 3 years after the immediately preceding inspection, 
whichever occurs earlier;
    (f) If serrations are not fully mated, or if any loose bolt is 
detected during the inspections required by paragraph (e) of this 
AD, prior to further flight, accomplish either Figure 1 or Figure 2 
of Boeing Service Bulletin 727-32-0383, Revision 1, dated January 
30, 1992.
    (1) If Figure 1 of the service bulletin is accomplished, repeat 
the inspection required by paragraph (e) of this AD at intervals not 
to exceed 3,700 flight cycles or 3 years after the immediately 
preceding inspection, whichever occurs earlier.
    (2) Accomplishment of Figure 2 of the service bulletin 
constitutes terminating action for the inspection requirements of 
paragraph (e) of this AD.
    (g) Accomplishment of the actions specified in either paragraphs 
(g)(1) or (g)(2) of this AD constitutes terminating action for all 
of the requirements of this AD.
    (1) Replace the currently installed aluminum rib fitting with a 
new steel rib fitting in accordance with Boeing Alert Service 
Bulletin 727-32A0399, dated July 13, 1995. Or
    (2) Modify the rib fitting assembly in accordance with Boeing 
Alert Service Bulletin 727-32A0399, dated July 13, 1995, and 
accomplish the follow-on actions specified in Figure 4 of the alert 
service bulletin.
    (h) As of the effective date of this AD, no person shall install 
an aluminum rib fitting on any airplane unless that fitting has been 
previously modified in accordance with Boeing Alert Service Bulletin 
727-32A0399, dated July 13, 1995.
    (i) 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.
    (j) 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.

    Issued in Renton, Washington, on March 26, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-7856 Filed 3-29-96; 8:45 am]
BILLING CODE 4910-13-U