74-11-01 MITSUBISHI HEAVY INDUSTRIES, LTD: Amendment 39-1844 as amended by Amendment 39-1859 is further amended by Amendment 39-3125. Applies to Mitsubishi Models MU-2B, MU-2B-10, MU-2B-15, MU-2B-20, MU-2B-25, MU-2B-30, and MU-2B-35 airplanes except those airplanes modified in accordance with Mitsubishi Service Recommendation No. 027 dated September 12, 1974, or an FAA-approved equivalent.
Compliance is required as indicated.
To detect cracks and optical distortion in the front windshield outer panes that could result from the discharge of unusually hot defogging air caused by an air conditioning system failure, accomplish the following:
(a) Before further flight and thereafter prior to the first takeoff each day, from outside the aircraft, visually check the outer lower edge of the left hand and right hand front windshield outer panes for cracks and small oval shaped optical distortions. The check required by this AD may be performed by the pilot.
NOTE: Distortions generally appear at the same intervals as those of the defogging air outlet holes, approximately 0.5 inches apart, and in an area approximately 0.8 inches above the top of the outside bottom windshield retainer edge. Particular attention should be given to these areas during the checks required by paragraph (a).
(b) If cracks or small oval shaped optical distortions are found during a check required by paragraph (a), before further flight, accomplish the following and continue to check in accordance with paragraph (a) of this AD:
(1) Replace the windshield outer pane in which a crack or optical distortion is found in accordance with the performance rules of FAR 43.13.
NOTE: Mitsubishi replacement windshield part numbers are as follows: Aircraft with electrically heated windshields incorporated in accordance with Mitsubishi Service Recommendation No. 014 - Windshield part numbers 010A-931026-11 and -12. Other Aircraft - Serial numbers 4 through and including 7 - Windshield partnumbers 010A-310260-1 and -2; Serial numbers 8 and up -Windshield part numbers 010A-31450-1 and -2.
(2) Correct the malfunctioning of the air conditioning system in accordance with the performance rules of FAR 43.13.
(c) Notwithstanding the compliance time for repair specified in paragraph (b) of this AD, the aircraft may be flown in accordance with FAR 21.197 to a base where the repair can be performed; provided that, the aircraft is not pressurized.
NOTE: Mitsubishi Heavy Industries Limited MU-2 Service Bulletin No. 163, dated March 4, 1974, pertains to this subject. Mitsubishi Maintenance Manuals for the Model MU-2B and MU-2B-10, -15, -20, -25, -30, and -35 airplanes contain information relating to the replacement of windshield panes and the trouble shooting of cabin air conditioning systems.
Amendment 39-1844 was effective upon publication in the Federal Register as to all persons except those persons to whom it was made effective upon receipt of the airmail letter dated April 19, 1974, that contained this amendment.
Amendment 39-1859 became effective upon publication in the Federal Register.
This Amendment 39-3125 becomes effective January 30, 1978.