Federal Register / Vol. 63, No. 1 / Friday, January 2, 1998 / Notices 137

DEPARTMENT OF TRANSPORTATION

Federal Aviation Administration

Proposed Advisory Circular (AC) 120–

XX, Repair Assessment of Pressurized

Fuselages

AGENCY: Federal Aviation

Administration (FAA), DOT.

ACTION: Notice of proposed advisory

circular.

SUMMARY: This notice invites pubic

comment on a proposed Advisory

Circular (AC) which provides guidance

as to acceptable means of accomplishing

the requirements of a proposed rule on

the subject of repair assessment of

pressurized fuselages published

elsewhere in the issue of the Federal

Register

DATES: Comments must be received on

or before April 2, 1998.

ADDRESSES: Send all comments on the

proposed AC to: Dorenda Baker,

Manager, Aging Aircraft Program,

ANM–109, FAA Transport Airplane

Directorate, Aircraft Certification

Service, 1601 Lind Ave SW., Renton,

WA 98055–4056. Comments may be

examined at the above address between

7:30 a.m. and 4:00 p.m. weekdays,

except Federal holidays.

FOR FURTHER INFORMATION CONTACT:

Pat Siegrist, Regulations Branch, ANM–

114, FAA Transport Airplane

Directorate, Aircraft Certification

Service, 1601 Lind Avenue SW.,

Renton, WA 98055–4056; telephone

(425) 227–2126.

SUPPLEMENTARY INFORMATION:

Comments Invited

A copy of the subject AC may be

obtained by contacting the person

named above under FOR FURTHER

INFORMATION CONTACT. Interested

persons are invited to comment on the

proposed AC by submitting such written

data, views, or arguments as they may

desire. Commenters must identify the

title of the AC and submit comments in

duplicate to the address specified above.

All comments received on or before the

closing date for comments will be

considered by the Transport Airplane

Directorate before issuing the final AC.

Discussion

Advisory Circular (AC) 120–xx,

Repair Assessment of Pressurized

Fuselages, has been written to provide

guidance on how to incorporate FAAapproved repair assessment guidelines

into an operator’s FAA-approved

maintenance or inspection program as

proposed in [insert notice number],

published elsewhere in this issue of the

Federal Register. The draft AC provides

proposed guidance as to acceptable

means of accomplishing the

requirements of the rule. The following

is a summary of the contents of the AC:

1. Repair Assessment Process.

Assessment of existing repairs installed

on the fuselage pressure boundary of

affected airplanes will establish a

damage-tolerance based structural

inspection program and replacement

times, where needed. Utilizing the

repair assessment guidelines developed

by the manufacturers of the affected

airplanes, two principle techniques

have been identified that can be used to

accomplish the repair assessment.

2. Implementation. The proposed rule

would require the repair assessment

guidelines to be approved by the

Aircraft Certification Office having

cognizance over the type certificate for

the affected airplane. The means by

which the repair assessment guidelines

would be incorporated into the FAAapproved maintenance or inspection

program would be subject to the

approval of the certificate holder’s

principle maintenance inspector (PMI)

or other cognizant airworthiness

inspector.

3. Recommended schedule for

accomplishing the repair assessment.

The repair assessment activity should be

completed in accordance with the

schedule in the FAA Approved Repair

Assessment Guidelines for each of the

affected airplanes. Any necessary

corrective actions to be taken as a result

of the evaluation would be incorporated

into the FAA-approved maintenance or

inspection program.

4. New Repairs. The operator would

have to assess new repairs using the

assessment guidelines, unless the new

repairs are accomplished according to

structural repair manuals, or any other

equivalent method that incorporates

damage tolerance methods of design and

evaluation. The aircraft manufacturers

of the affected models are updating their

structural repair manuals to address

damage tolerance methodology. FAA

Advisory Circular 25.1529–1,

‘‘Instructions for Continued

Airworthiness of Structural Repairs on

transport Airplanes,’’ provides guidance

for installing new damage tolerance

based repairs.

5. Sale and Transfer of Airplanes.

Before an airplane is added to an

operator’s operations specifications, a

program for accomplishment of the

repair assessment should be established.

6. Repairs to Structural Modification

Certified by a Supplemental Type

Certificate (STC). The operator would

need to establish a repair assessment

program for structure modified by an

STC.

Issued in Washington, D.C. on December

22, 1997.

Thomas E. McSweeny,

Director, Aircraft Certification Service.

[FR Doc. 97–34159 Filed 12–31–97; 8:45 am]

BILLING CODE 4910–13–M