Airworthiness Directives; Boeing Model 767-200 and -300 Series Airplanes

SUMMARY: This document publishes in the Federal Register an amendment

adopting Airworthiness Directive (AD) T95-20-51 that was sent

previously to all known U.S. owners and operators of Boeing Model 767-

200 and -300 series airplanes by individual telegrams. This AD requires

inspections of the lower half of the aft trunnion of the main landing

gear (MLG) to detect damage, cracking, missing pieces, or corrosion;

and correction of discrepancies. This amendment is prompted by a report

indicating that the MLG collapsed on an airplane due to fracture of the

aft trunnion outer cylinder that was caused by stress corrosion

cracking. The actions specified by this AD are intended to prevent the

collapse of the MLG due to the problems associated with stress

corrosion cracking in the aft trunnion assembly; collapse of the MLG

could lead to loss of control of the airplane during landing, taxiing,

and takeoff.

DATES: Effective October 17, 1995, to all persons except those persons

to whom it was made immediately effective by telegraphic AD T95-20-51,

issued September 25, 1995, which contained the requirements of this

amendment. -

Comments for inclusion in the Rules Docket must be received on or

before December 11, 1995.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

Administration (FAA), Transport Airplane Directorate, ANM-103,

Attention: Rules Docket No. 95-NM-190-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056. -

Information concerning this AD may be examined at the FAA,

Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton,

Washington.

FOR FURTHER INFORMATION CONTACT: James G. Rehrl, Aerospace Engineer,

Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle

Aircraft Certification Office, 1601 Lind Avenue, SW., Renton,

Washington 98055-4056; telephone (206) 227-2783; fax (206) 227-1181.

SUPPLEMENTARY INFORMATION: On September 7, 1995, the FAA issued AD 95-

19-10, amendment 39-9372 (60 FR 47689, September 14, 1995), applicable

to all Boeing Model 767 series airplanes. That AD requires operators to

perform visual inspections of the outer cylinder aft trunnion on the

main landing gear (MLG) to determine if the fillet seal is cracked or

missing, and to correct any discrepancy or to perform follow-on

actions, if necessary. That action was prompted by reports of fractures

of the outer cylinder aft trunnion due to stress corrosion cracking. -

Since the issuance of that AD, the FAA has received an additional

report indicating that the MLG collapsed on a Model 767-300 series

airplane due to fracture of the aft trunnion outer cylinder that was

caused by stress corrosion cracking. In this reported incident, the

right-hand MLG separated from the aft and forward trunnion support

structure and penetrated the wing trailing edge. The airplane rolled to

the right and came to rest on the right engine nacelle. Extensive

damage occurred to the right-hand MLG and its support structure, the

wing trailing edge, and the right engine and its support structure.

Investigation revealed that this fracture differed from those reported

previously in that it initiated at the crossbolt hole, approximately

five inches from the aft trunnion bushing flange. -

Stress corrosion cracking in the outer cylinder of the aft

trunnion, if not corrected, could result in the collapse of the MLG

under certain loading conditions. Such a collapse could lead to the

loss of control of the airplane during landing, taxiing, and takeoff. -

Consequently, the FAA has determined that the problem of stress

corrosion cracking is not limited solely to the aft trunnion bushing,

which was addressed in AD 95-19-10. The FAA finds that additional

inspections must be performed in an expanded area of the aft trunnion

assembly to ensure the safety of the affected fleet. These additional

inspections must be performed in addition to, not in lieu of, the

inspections required by AD 95-19-10. -

Since the unsafe condition described is likely to exist or develop

on other airplanes of the same type design, the FAA issued Telegraphic

AD T95-20-51 to prevent the collapse of the MLG due to the problems

associated with stress corrosion cracking in the aft trunnion assembly.

The AD requires operators to perform an external general visual

inspection of the lower half of the aft trunnion of the MLG to detect

damage, cracking, missing pieces, or corrosion emanating from the aft

trunnion bushing fillet seal or from the aft trunnion crossbolt hole.

(This inspection is to be performed repetitively on airplanes having

MLG's that are 4 years old or older.) Discrepancies are to be repaired

in accordance with a method approved by the FAA. -

Since it was found that immediate corrective action was required,

notice and opportunity for prior public comment thereon were

impracticable and contrary to the public interest, and good cause

existed to make the AD effective immediately by individual telegrams

issued on September 25, 1995, to all known U.S. owners and operators of

Boeing Model 767-200 and -300 series airplanes. These conditions still

exist, and the AD is hereby published in the Federal Register as an

amendment to section 39.13 of the Federal Aviation Regulations (14 CFR

39.13) to make it effective to all persons.

The FAA considers this AD to be interim action until final action

is identified, at which time the FAA may consider further rulemaking.

Comments Invited

Although this action is in the form of a final rule that involves

requirements affecting flight safety and, thus, was not preceded by

notice and an opportunity for public comment, comments are invited on

this rule. Interested persons

[[Page 53110]]

are invited to comment on this 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 under the caption ADDRESSES. All communications received on

or before the closing date for comments will be considered, and this

rule may be amended in light of the comments received. Factual

information that supports the commenter's ideas and suggestions is

extremely helpful in evaluating the effectiveness of the AD action and

determining whether additional rulemaking action would be needed. -

Comments are specifically invited on the overall regulatory,

economic, environmental, and energy aspects of the rule that might

suggest a need to modify the 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 that

summarizes each FAA-public contact concerned with the substance of this

AD will be filed in the Rules Docket. -

Commenters wishing the FAA to acknowledge receipt of their comments

submitted in response to this rule must submit a self-addressed,

stamped postcard on which the following statement is made: ``Comments

to Docket Number 95-NM-190-AD.'' The postcard will be date stamped and

returned to the commenter. -

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. -

The FAA has determined that this regulation is an emergency

regulation that must be issued immediately to correct an unsafe

condition in aircraft, and that it is not a ``significant regulatory

action'' under Executive Order 12866. It has been determined further

that this action involves an emergency regulation under DOT Regulatory

Policies and Procedures (44 FR 11034, February 26, 1979). If it is

determined that this emergency regulation otherwise would be

significant under DOT Regulatory Policies and Procedures, a final

regulatory evaluation will be prepared and placed in the Rules Docket.

A copy of it, if filed, 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, 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 USC 106(g), 40101, 40113, 44701.

Sec. 39.13 [Amended] -

2. Section 39.13 is amended by adding the following new

airworthiness directive:

95-20-51 Boeing: Amendment 39-9398. Docket 95-NM-190-AD.

-Applicability: All Model 767-200 and 767-300 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 use the authority

provided in paragraph (d) 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 prevent the collapse of the main landing gear due to stress

corrosion cracking in the outer cylinder of the aft trunnion,

accomplish the following:

-Note 2: The inspections required by this AD are in addition to,

not in lieu of, the inspections required by AD 95-19-10, amendment

39-9372.

-(a) Within 48 clock hours (not flight hours) after the

effective date of this AD, perform an external general visual

inspection of the lower half of the aft trunnion of the main landing

gear (MLG) to detect obvious signs of damage, cracking, missing

pieces; or obvious visible corrosion emanating from the aft trunnion

bushing fillet seal or from the aft trunnion crossbolt hole.

-Note 3: For the purpose of this AD, ``external general visual

inspection'' means that the inspection is to be conducted within one

foot of the area to be inspected. If necessary, the area should be

wiped clean with a rag. Finally, mirrors and additional lighting

should be used, as needed, to increase the probability of visually

detecting discrepancies. This inspection does not require

disassembly of the MLG.

-(b) Prior to four years from the date the MLG is placed in

service or overhauled, or within 48 clock hours (not flight hours)

after the inspection required by paragraph (a) of this AD is

accomplished, whichever occurs later, repeat the inspection required

by paragraph (a) of this AD. Thereafter, repeat the inspection at

intervals not to exceed 48 clock hours. -

(c) If any discrepancy is detected during any inspection

required by this AD, prior to further flight, repair in accordance

with a method approved by the Manager, Seattle Aircraft

Certification Office (ACO), FAA, Transport Airplane Directorate. -

(d) 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 ACO. 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 4: Information concerning the existence of approved

alternative methods of compliance with this AD, if any, may be

obtained from the Seattle ACO.

-(e) 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. -

(f) This amendment becomes effective on October 17, 1995, to all

persons except those persons to whom it was made immediately

effective by telegraphic AD T95-20-51, issued on September 25, 1995,

which contained the requirements of this amendment.

Issued in Renton, Washington, on October 4, 1995.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 95-25157 Filed 10-11-95; 8:45 am]

BILLING CODE 4910-13-U