AD 90-21-16

90-21-16 SAAB-SCANIA: Amendment 39-6763. Docket No. 90-NM-111-AD. Applicability: Model SF-340A series airplanes, Serial Numbers 004 through 159, certified in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent loss of climb performance during single engine operation (i.e. one engine failed), and latent failures in the engine control unit, accomplish the following:

A. Within 60 days after November 20, 1989 (the effective date of Amendment 39-6361, AD 89- 22-08), install modified electrical control units (ECU) in accordance with General Electric Service Bulletin 74-16, dated March 22, 1989.

B. Within 60 days after the effective date of this amendment, remove any relays and associated wiring previously installed in accordance with SAAB-Scania Service Bulletins SAAB SF340- 61-020 and SAAB SF340-77-003, in accordance with the procedures specified in SAAB-SCANIA Service Bulletin SF340-77-006, dated March 9, 1990.

C. After completion of paragraphs A. and B. of this AD, delete steps referencing "Applicable With Mod. No. 1931" in the Emergency Procedures Section and Normal Procedures Expanded Checklist of the FAA-approved Airplane Flight Manual (AFM).

D. 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.

E. 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 SAAB-SCANIA, Aircraft Division, S.58188, Linkoping, Sweden. These documents may be examined at the FAA, Northwest Mountain Region, Transport Airplane Directorate, 1601 Lind Avenue S.W., Renton, Washington.

Airworthiness Directive 90-21-16 supersedes AD 89-22-08, Amendment 39- 6361.

This amendment (39-6763, AD 90-21-16) becomes effective on November 14, 1990.