AD 80-03-04

80-03-04 MCDONNELL DOUGLAS: Amendment 39-3684. Applies to McDonnell Douglas Model DC-9, Series 10, 20, 30, 40, and 50 airplanes and Military C-9 series airplanes certificated in all categories, not incorporating McDonnell Douglas Service Bulletin 49-25 dated November 10, 1973 or the production equivalent of this service bulletin.

To prevent fire hazard caused by possible accumulation of fuel from APU false-starts collecting on lower aft fuselage inner surface, accomplish the following:

(a) Within the next 100 hours' time in service from the effective date of this AD unless already accomplished within the last 150 hours' time in service, and thereafter intervals not to exceed 250 hours' time in service from the last inspection, accomplish the following:

(1) Verify that the area adjacent to and above the fuselage drain hole located after the pressure bulkhead at the 5 o'clock position is clear of debris and an open drain path is evident. Clean if necessary to removedebris; insure that the lower edge of the aft pressure bulkhead insulation blanket does not obstruct the drainhole, and

(2) Check tail compartment for any spilled fuel and clean before starting APU.

(b) Within 100 hours' time in service from the effective date of this AD:

(1) Record in the aircraft logbook all occurrences of APU false starts.

(2) Prior to restart attempt after false start occurrence, check for open drain hole at 5 o'clock position and check for any fuel spills in the aft compartment and clean before restart attempt.

(3) Install placard in cockpit and revise AFM to read, "Do not attempt to restart APU after a false start until check of drain and AFT fuselage has been accomplished."

The checks required by paragraph (b)(2) of this AD may be performed by the flight crew.

NOTE: A maintenance record entry showing compliance and method of compliance with this AD is required by FAR 91.173 and FAR 121.380.

(c) Within one year's timein service from the effective date of this AD, unless already accomplished, incorporate the APU exhaust system modification consisting of a baffle on the exhaust duct assembly which diverts residual fuel away from the expansion joint, per McDonnell Douglas Service Bulletin 49-25, dated November 10, 1973.

(d) Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base for the accomplishment of inspections, modifications or repairs required by this AD.

(e) Alternative inspections, modifications or other actions which provide an equivalent level of safety may be used when approved by the Chief, Aircraft Engineering Division, FAA Western Region.

This amendment becomes effective February 11, 1980.