AD 95-01-06

Effective January 24, 1995.

The incorporation by reference of certain publications listed in the regulations is approved by the Director of the Federal Register as of January 24, 1995.

Comments for inclusion in the Rules Docket must be received on or before March 10, 1995.

Submit comments in triplicate to the Federal Aviation Administration (FAA), Transport Airplane Directorate, ANM-103, Attention: Rules Docket No. 94-NM-247-AD, 1601 Lind Avenue, SW., Renton, Washington 98055-4056.

The service information referenced in this AD may be obtained from Pemco Aeroplex, Inc., P.O. Box 2287, Birmingham, Alabama 35201-2287. This information may be examined at the FAA, Transport Airplane Directorate, 1601 Lind Avenue, SW., Renton, Washington; or at the FAA, Small Airplane Directorate, Atlanta Aircraft Certification Office, Campus Building, 1701 Columbia Avenue, Suite 2-160, College Park, Georgia; or at the Office of the Federal Register, 800 North Capitol Street, NW., suite 700, Washington, DC.

Curtis Jackson, Aerospace Engineer, Airframe Branch, ACE-120A; FAA, Small Airplane Directorate, Atlanta Aircraft Certification Office, Campus Building, 1701 Columbia Avenue, Suite 2-160, College Park, Georgia 30337-2748; telephone (404) 305-7358; fax (404) 305-7348; or Della Swartz, Aerospace Engineer, Airframe Branch, ANM-120S, FAA, Transport Airplane Directorate, Seattle Aircraft Certification Office, 1601 Lind Avenue, SW., Renton, Washington 98055-4056; telephone (206) 227-2785; fax (206) 227-1181.

Recently, an operator reported that it experienced difficulty in pressurizing a Boeing Model 737-300 series airplane. Investigation revealed that the airplane could not be pressurized because the main deck cargo door would not seal properly. Further investigation revealed that 13 of the 16 support angles on the lower jamb of the main deck cargo door [[Page 2324]] had failed due to premature fatigue cracking.

Following this incident, the FAA has received additional reports from operators of Boeing Model 737-200 and -300 series airplanes of fatigue cracking on the support angles on the lower jamb of the main deck cargo door.

Pemco Aeroplex installed main deck cargo doors on all of these airplanes in accordance with supplemental type certificate (STC) SA2969SO. Several of these airplanes had accumulated less than 4,000 total flight cycles since installation of the main deck cargo door.

Such cracking, if not detected and corrected in a timely manner, could result in in-flight separation of the main deck cargo door from the airplane.

The FAA has reviewed and approved Pemco Alert Service Letter 737-53-0003, Revision 3, dated December 22, 1994, which describes procedures for repetitive visual inspections to detect cracking in the radii on the support angles on the lower jamb of the main deck cargo door and replacement of cracked parts with new parts. This service letter permits further flight with parts that are cracked within certain limits.

Since an unsafe condition has been identified that is likely to exist or develop on other airplanes of the same type design, this AD is being issued to prevent in-flight separation of the main deck cargo door from the airplane. This AD requires repetitive visual inspections to detect cracking in the radii on the support angles on the lower jamb of the main deck cargo door and replacement of cracked parts with new parts. The actions are required to be accomplished in accordance with the service letter described previously. However, unlike the service letter, this AD does not permit further flight with cracked parts. The FAA has determined that all cracked parts must be replaced prior to further flight.

This is considered to be interim action until final action is identified, at which time the FAA may consider further rulemaking.

As a result of recent communications with the Air Transport Association (ATA) of America, the FAA has learned that, in general, some operators may misunderstand the legal effect of AD's on airplanes that are identified in the applicability provision of the AD, but that have been altered or repaired in the area addressed by the AD. The FAA points out that all airplanes identified in the applicability provision of an AD are legally subject to the AD. If an airplane has been altered or repaired in the affected area in such a way as to affect compliance with the AD, the owner or operator is required to obtain FAA approval for an alternative method of compliance with the AD, in accordance with the paragraph of each AD that provides for such approvals. A note has been included in this rule to clarify this requirement.

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.

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 rule must submit a self-addressed, stamped postcard on which the following statement is made: ``Comments to Docket Number 94-NM-247-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.

Air transportation, Aircraft, Aviation safety, Incorporation by reference, Safety.

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:

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.