1AD/B737/23 Amdt 3 - Forward Service Doorway Aft Frame

COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 105 CIVIL AVIATION SAFETY AUTHORITY

SCHEDULE OF AIRWORTHINESS DIRECTIVES

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Boeing 737 Series Aeroplanes

AD/B737/23

Amdt 3

Forward Service Doorway Aft Frame 1/99

Applicability: Model 737 series aircraft, as listed in Boeing Service Bulletin 737-53A1108, Revision 5, dated October 26, 1989.

Requirement: Perform visual inspection in accordance with the technical requirements of FAA AD 98-22-10 Amdt 39-10858.

Compliance: As specified in the Requirement Document with a revised effective date of 28 January 1999.

This Amendment becomes effective on 28 January 1999.

Background: Four operators reported cracks on eleven aircraft with 19,200 to 51,300 flight cycles. Two adjacent cracked door stops could result in door deflection with possible major structural damage and loss of pressurisation. Amendment 1 clarified terminating action for the inspections. Amendment 2 reduced the inspection threshold to be consistent with the cracking history.

Amendment 3 is issued in response to a new FAA AD prompted by reports that repetitive inspections required by the existing FAA AD may not detect cracking of the aft frame and aft frame support structure of the forward service doorway in a timely manner. The initial inspection and repetitive inspection intervals are reduced, certain repetitive inspections are added, and provision is made for optional terminating action for the repetitive inspection requirements.

Amendment 2 of this Airworthiness Directive became effective on 28 December 1989.

Amendment 1 of this Airworthiness Directive became effective on 2 November 1989.

The original issue of this Airworthiness Directive became effective on 10 August 1989.