90-21-20: Relay box wiring & angle of attack sensors

90-21-20 AIRBUS INDUSTRIE: Amendment 39-6770. Docket No. 90-NM-91-AD. Applicability: All Model A320-111, A320-211, and A320-231 series airplanes, certificated in any category. Compliance: Required within the next 350 hours time-in-service after the effective date of this AD, unless previously accomplished. To prevent the simultaneous activation in flight of two angle of attack sensors and subsequent incorrect pitch-down command to the elevator, accomplish the following: A. Perform one of the following: 1. Disconnect and modify the wiring in the relay box 103VU, in Zone 127, and in Zone 232, in accordance with Airbus Industrie Service Bulletin A320-34-1012, Revision 1, dated April 10, 1990; or Revision 2, dated June 8, 1990; or 2. Accomplish Modification No. 21824P1953, which consists of moving the test control wires of the angle of attack sensors, in accordance with Airbus Industrie Service Bulletin A320-34-1013, dated June 1, 1990. B. An alternate means of compliance or adjustment of the compliance time, which provides an acceptable level of safety, may be used when approved by the Manager, Standardization Branch, ANM-113, FAA, Transport Airplane Directorate. NOTE: The request should be submitted directly to the Manager, Standardization Branch, ANM-113, and a copy sent to the cognizant FAA Principal Inspector (PI). The PI will then forward comments or concurrence to the Manager, Standardization Branch, ANM-113. C. Special flight permits may be issued in accordance with FAR 21.197 and 21.199 to operate airplanes to a base in order to comply with the requirements of this AD. All persons affected by this directive who have not already received the appropriate service documents from the manufacturer may obtain copies upon request to Airbus Industrie, Airbus Support Division, Avenue Didier Daurat, 31700 Blagnac, France. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington. This amendment (39-6770, AD 90-21-20) becomes effective November 19, 1990.