Airworthiness Directives; McDonnell Douglas Model DC-9 and C-9 (Military) Series Airplanes

DEPARTMENT OF TRANSPORTATION

14 CFR Part 39

[Docket No. 93-NM-224-AD; Amendment 39-8790; AD 94-01-08]

Airworthiness Directives; McDonnell Douglas Model DC-9 and C-9

(Military) Series Airplanes

AGENCY: Federal Aviation Administration, DOT.

ACTION: Final rule; request for comments.

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SUMMARY: This amendment adopts a new airworthiness directive (AD) that

is applicable to certain McDonnell Douglas Model DC-9 and C-9

(military) series airplanes. This action requires inspections to detect

cracking in the ventral aft pressure bulkhead, and repair, if

necessary. This amendment is prompted by reports of cracking found in

the ventral aft pressure bulkhead on several airplanes. The actions

specified in this AD are intended to prevent the propagation of cracks

in the ventral aft pressure bulkhead, which could lead to failure of

the bulkhead and subsequent rapid decompression of the airplane.

DATES: Effective January 28, 1994.

The incorporation by reference of certain publications listed in

the regulations is approved by the Director of the Federal Register as

of January 28, 1994.

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

before March 14, 1994.

ADDRESSES: Submit comments in triplicate to the Federal Aviation

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

Attention: Rules Docket No. 93-NM-224-AD, 1601 Lind Avenue, SW.,

Renton, Washington 98055-4056.

The service information referenced in this AD may be obtained from

McDonnell Douglas Corporation, P. O. Box 1771, Long Beach, California

90846-0001, Attention: Business Unit Manager, Technical Publications,

C1-HDR (54-60). This information may be examined at the FAA, Transport

Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at

the Los Angeles Aircraft Certification Office, FAA, Transport Airplane

Directorate, 3229 East Spring Street, Long Beach, California; or at the

Office of the Federal Register, 800 North Capitol Street NW., suite

700, Washington, DC.

FOR FURTHER INFORMATION CONTACT: David Y. J. Hsu, Airframe Branch, ANM-

120L, Los Angeles Aircraft Certification Office, FAA, Transport

Airplane Directorate, 3229 East Spring Street, Long Beach, California

90806-2425; telephone (310) 988-5325; fax (310) 988-5210.

SUPPLEMENTARY INFORMATION: The FAA has recently received reports of

cracking found in the ventral aft pressure bulkhead on several

McDonnell Douglas Model DC-9 series airplanes. Two operators reported

finding fatigue cracks on four airplanes in both the left- and right-

hand side ventral aft pressure bulkhead web and doublers, between water

lines (stations) Z=43.000 and Z=74.000. The length of the reported

cracks found in the webs ranged from 5 inches to 48 inches. The webs of

each of the cracked bulkheads on the subject airplanes were made of

2014-T6 material and were 0.042 inch thick. It is suspected that

fatigue is the cause of the cracks. The affected airplanes had

accumulated between 73,803 and 83,760 landings at the time of the crack

findings. In each case, the cracking was found during inspections that

were outside of the operator's normal maintenance program schedule.

Currently, there is no requirement for regular inspection of the

affected area of the bulkhead. Cracking in the ventral aft pressure

bulkhead web or doublers, if allowed to propagate to a critical length,

could lead to failure of the bulkhead, extensive structural damage, and

subsequent rapid decompression of the airplane.

The FAA has reviewed and approved McDonnell Douglas DC-9 Alert

Service Bulletin A53-264, dated December 22, 1993, that describes

procedures for conducting repetitive visual, low frequency eddy

current, and high frequency eddy current inspections to detect cracking

in the ventral aft pressure bulkhead. The area of inspection includes

the upper left and right sides of the ventral aft pressure bulkhead in

the area of the finger doublers and web between stations Z=34.000 and

Z=74.000, from the edge of the ventral doorway outboard and upward

along the edge of the doublers. -

Since an unsafe condition has been identified that is likely to

exist or develop on other Model DC-9 and C-9 (military) series

airplanes of the same type design, this AD is being issued to prevent

failure of the ventral aft pressure bulkhead due to cracking. This AD

requires repetitive visual, low frequency eddy current, and high

frequency eddy current inspections to detect cracking in the ventral

aft pressure bulkhead. These inspections are required to be

accomplished in accordance with the service bulletin described

previously. Any cracks found are required to be repaired, prior to

further flight, in accordance with a method approved by the FAA.

Additionally, operators are required to submit a report of initial

inspection findings to the FAA.

This is considered to be interim action until final action is

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

Since a situation exists that requires the immediate adoption of

this regulation, it is found that notice and opportunity for prior

public comment hereon are impracticable, and that good cause exists for

making this amendment effective in less than 30 days.

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 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 notice must submit a self-addressed,

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

to Docket Number 93-NM-224-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 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, Incorporation by

reference, Safety.

Adoption of the Amendment

Accordingly, pursuant to the authority delegated to me by the

Administrator, the Federal Aviation Administration amends 14 CFR part

39 of the Federal Aviation Regulations 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 adding the following new

airworthiness directive:

94-01-08 McDonnell Douglas: Amendment 39-8790. Docket 93-NM-224-AD.

-Applicability: Model DC-9 and C-9 (military) series airplanes,

as listed in McDonnell Douglas DC-9 Alert Service Bulletin A53-264,

dated December 22, 1993; equipped with a ventral aft pressure

bulkhead web composed of 2014-T6 material that is 0.042 inch thick;

certificated in any category.

Compliance: Required as indicated, unless accomplished

previously.

To prevent failure of the aft pressure bulkhead due to cracking,

accomplish the following:

(a) For airplanes on which the procedures specified in McDonnell

Douglas DC-9 Service Bulletins 53-26 and A53-144, or production

equivalent, have not been accomplished (Group I airplanes): Upon the

accumulation of 50,000 total landings, or within 30 days after the

effective date of this AD, whichever occurs later, conduct an

initial visual, low frequency eddy current, and high frequency eddy

current inspection to detect cracks in the ventral aft pressure

bulkhead, in accordance with McDonnell Douglas DC-9 Alert Service

Bulletin A53-264, dated December 22, 1993.

(1) If no crack is detected during any of the inspections,

repeat these inspections at intervals not to exceed 1,500 landings.

-

(2) If any crack is detected during any of the inspections,

prior to further flight, repair in accordance with a method approved

by the Manager, Los Angeles Aircraft Certification Office (ACO),

FAA, Transport Airplane Directorate. -

(b) For airplanes on which the procedures specified in McDonnell

Douglas DC-9 Service Bulletins 53-26 and A53-144, or production

equivalent, have previously been accomplished (Group II airplanes):

Upon the accumulation of 60,000 total landings, or within 60 days

after the effective date of this AD, whichever occurs later, conduct

an initial visual, low frequency eddy current, and high frequency

eddy current inspection to detect cracks in the ventral aft pressure

bulkhead, in accordance with McDonnell Douglas DC-9 Alert Service

Bulletin A53-264, dated December 22, 1993.

(1) If no crack is detected during any of the inspections,

repeat these inspections at intervals not to exceed 1,500 landings.

-

(2) If any crack is detected during any of the inspections,

prior to further flight, repair in accordance with a method approved

by the Manager, Los Angeles ACO, FAA, Transport Airplane

Directorate.

(c) Within 10 calendar days after accomplishing the initial

inspection required by paragraph (a) or (b) of this AD, as

applicable, submit a report of inspection findings, both positive

and negative, to the Manager, Los Angles ACO, FAA, Transport

Airplane Directorate, 3229 East Spring Street, Long Beach,

California 90806-2425; fax (310) 988-5210. The report must include

the following information: -

(1) Factory serial number of the airplane;

(2) Total time and flight cycles on the airplane;

(3) A detailed description of the discrepancy finding;

(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, Los Angeles 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, Los Angeles ACO.

-Note: Information concerning the existence of approved

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

obtained from the Los Angeles ACO.

(e) Special flight permits may be issued in accordance with FAR

21.197 and 21.199 to operate the airplane to a location where the

requirements of this AD can be accomplished.

(f) The inspections shall be done in accordance with McDonnell

Douglas DC-9 Alert Service Bulletin A53-264, dated December 22,

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 McDonnell Douglas Corporation,

P. O. Box 1771, Long Beach, California 90846-0001, Attention:

Business Unit Manager, Technical Publications, C1-HDR (54-60).

Copies may be inspected at the FAA, Transport Airplane Directorate,

1601 Lind Avenue SW., Renton, Washington; or at the Los Angeles

Aircraft Certification Office, FAA, Transport Airplane Directorate,

3229 East Spring Street, Long Beach, California; or at the Office of

the Federal Register, 800 North Capitol Street, NW., suite 700,

Washington, DC.

(g) This amendment becomes effective on January 28, 1994.

Issued in Renton, Washington, on January 3, 1994.

Darrell M. Pederson,

Acting Manager, Transport Airplane Directorate, Aircraft Certification

Service.

[FR Doc. 94-345 Filed 1-12-94; 8:45 am]

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