[Federal Register Volume 61, Number 63 (Monday, April 1, 1996)]
[Proposed Rules]
[Pages 14271-14273]
From the Federal Register Online via the Government Publishing Office [www.gpo.gov]
[FR Doc No: 96-7855]



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DEPARTMENT OF TRANSPORTATION
14 CFR Part 39

[Docket No. 95-NM-223-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 the supersedure of an existing 
airworthiness directive (AD), applicable to all Boeing Model 727 series 
airplanes, that currently requires inspections to detect cracking of 
the actuator rib fitting of the inboard door of the main landing gear 
(MLG); and rework or replacement of any cracked fitting. That action 
was prompted by reports that the MLG failed to extend for a landing due 
to a fractured rib fitting. This action would require inspections to 
detect cracking in an expanded area of the actuator rib fitting, and 
various follow-on actions. This action is prompted by a report of a 
fractured rib fitting that had been reworked in accordance with the 
existing AD. The actions specified by the proposed 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.

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

ADDRESSES: Submit comments in triplicate to the Federal Aviation

[[Page 14272]]
Administration (FAA), Transport Airplane Directorate, ANM-103, 
Attention: Rules Docket No. 95-NM-223-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 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-223-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-223-AD, 1601 Lind Avenue, SW., Renton, Washington 
98055-4056.

Discussion -

    On December 15, 1989, the FAA issued AD 90-02-19, amendment 39-6433 
(55 FR 601, January 8, 1990), applicable to all Boeing Model 727 series 
airplanes, to require inspections to detect cracking of the actuator 
rib fitting of the inboard door of the main landing gear (MLG); and 
rework or replacement of any cracked fitting with a reworked or new 
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. -
    Additionally, on January 11, 1993, the FAA issued AD 93-01-14, 
amendment 39-8468 (58 FR 5574, January 22, 1993). That AD requires 
inspections to detect loose attach fitting bolts of the door actuator 
of the MLG, inspections to determine whether serrations are fully 
mated, and various follow-on corrective actions. The requirements of 
that AD are intended to prevent landing with one MLG partially 
extended. -
    Since the issuance of those AD's, the FAA has received an 
additional report of an MLG on a Model 727 series airplane failing to 
extend for landing, due to a fractured rib fitting. The broken rib 
fitting caused the MLG door and MLG to retract improperly (out of 
sequence), which led to the MLG jamming against the MLG door. That 
airplane had accumulated 34,038 flight hours and 22,776 landings. The 
fitting on that airplane had been reworked in accordance with the 
requirements of AD 90-02-19; no follow-on inspections of the fitting 
were required by that AD. Further, the area of inspection specified by 
AD 90-02-19 did not include the area of the fitting in which this most 
recent incident of cracking was found. -
    The FAA has reviewed and approved Boeing Alert Service Bulletin 
727-32A0399, dated July 13, 1995. This alert service bulletin describes 
procedures for:
    1. Either a high frequency eddy current or dye penetrant inspection 
to detect cracking in an expanded area 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. Accomplishment of this 
modification and follow-on actions eliminates 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 when cracking is found. Accomplishment of this 
replacement eliminates the need for all of the inspections required by 
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 supersede AD 90-02-19 to require either a high 
frequency eddy current or dye penetrant inspection to detect cracking 
in an expanded area of the actuator rib fitting of the MLG, and various 
follow-on actions. -
    This proposed AD would also require modification of the rib fitting 
assembly, and either repetitive high frequency eddy current or dye 
penetrant inspections for cases in which no cracking is found. Such 
modification and repetitive inspections would terminate the 
requirements of AD 93-01-14. -
    This proposed AD would also require replacement of the currently 
installed aluminum rib fitting with a new steel rib fitting for 
findings of cracking. Such replacement would terminate the proposed 
requirement to inspect the fitting repetitively and would terminate the 
requirements of AD 93-01-14. The FAA is currently proposing, in a 
separate rulemaking action (reference Docket 95-NM-222-AD), to revise 
AD 93-01-14 to include this optional terminating action for the 
requirements of that AD. -
    The actions proposed by this AD would be required to be 
accomplished in accordance with the alert service bulletin described 
previously. -
    The FAA is not proposing to mandate replacement of the currently 
installed aluminum rib fittings that are not cracked. The FAA finds 
that modification of rib fitting assembly and follow-on actions will 
preclude fractured rib fittings of the MLG. -
    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 new actions that are proposed in this AD action would take 
approximately 10 work hours per

[[Page 14273]]
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 
proposed requirements of this AD is estimated to be $699,600, or $600 
per airplane. -
    The cost impact figures discussed above are based on assumptions 
that no operator has yet accomplished any of the current or 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 USC 106(g), 40113, 44701.


Sec. 39.13  [Amended] -

    2. Section 39.13 is amended by removing amendment 39-6433 (55 FR 
601, January 8, 1990), and by adding a new airworthiness directive 
(AD), to read as follows:

Boeing: Docket 95-NM-223-AD. Supersedes AD 90-02-19, Amendment 39-
6433.

    -Applicability: All Model 727 series 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 (f) 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 failure of the main landing gear (MLG) to extend for 
landing and subsequent damage to the airplane, accomplish the 
following:
    (a) Perform either a high frequency eddy current or dye 
penetrant inspection to detect cracking of the actuator rib fitting 
of the MLG in accordance with Boeing Alert Service Bulletin 727-
32A0399, dated July 13, 1995, at the later of the times specified in 
either paragraph (a)(1) or (a)(2) of this AD. -
    (1) Prior to the accumulation of 20,000 total flight cycles; or 
-
    (2) Prior to the accumulation of 1,000 flight cycles after the 
effective date of this AD, or within 2,500 flight cycles after the 
immediately preceding inspection performed in accordance with AD 90-
02-19, amendment 39-6433, whichever occurs earlier. -
    (b) If no cracking is detected during the inspection required by 
paragraph (a) of this AD, prior to further flight, modify the rib 
fitting assembly in accordance with Boeing Alert Service Bulletin 
727-32A0399, dated July 13, 1995. Within 7,500 flight cycles after 
accomplishing this modification, perform either a high frequency 
eddy current or dye penetrant inspection to detect cracking of the 
modified actuator rib fitting of the MLG in accordance with the 
alert service bulletin. Repeat the inspection thereafter at 
intervals not to exceed 2,500 flight cycles, until the fitting is 
replaced in accordance with paragraph (d) of this AD. -
    (c) If any cracking is detected during the inspections required 
by either paragraph (a) or (b) of this AD, prior to further flight, 
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. Such replacement constitutes 
terminating action for the requirements of this AD. -
    (d) Replacement of 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, constitutes terminating 
action for the requirements of this AD. -
    (e) 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. -
    (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.

    Issued in Renton, Washington, on March 26, 1996.
Darrell M. Pederson,
Acting Manager, Transport Airplane Directorate, Aircraft Certification 
Service.
[FR Doc. 96-7855 Filed 3-29-96; 8:45 am]
BILLING CODE 4910-13-P