AD 91-14-02

Final rule

91-14-02 SAAB-SCANIA: Amendment 39-7044. Docket No. 91-NM-28-AD. Supersedes AD 90-16-02.
Applicability: Model SF-340A series airplanes, Serial Numbers 031 through 159; and SAAB 340B series airplanes, Serial Numbers 160 through 186; certificated in any category.

Compliance: Required as indicated, unless previously accomplished.

To prevent inhibited airplane rudder control due to cracking in the vertical stabilizer top closure rib, accomplish the following:

A. Prior to the accumulation of 500 hours time-in-service since new or within 100 hours time- in-service after August 30, 1990 (the effective date of Amendment 39-6676, AD 90-16-02), whichever occurs later, inspect the vertical stabilizer top closure rib for evidence of cracking, in accordance with SAAB Service Bulletin 340-55-022, Revision 1, dated February 27, 1990.

B. If no evidence of cracking is found, reinspect the vertical stabilizer top closure rib for cracking at intervals not to exceed 500 flight hours time-in-service.

C. If cracking is found, prior to further flight, stop drill the ends of the cracks, blend, clean, and apply aluminum tape, as specified in SAAB Service Bulletin 340-55-022, Revision 1, dated February 27, 1990. Reinspect for additional cracking and the condition of the aluminum tape at intervals not to exceed 100 hours time-in-service.

D. Within one year after the effective date of this amendment, either replace the rib with a new thicker rib with a larger radius, or reinforce the rib and replace the attachment angle, in accordance with SAAB Service Bulletin 340-55-023, dated October 1, 1990. Accomplishment of either of these modifications constitutes terminating action for repetitive inspections required by paragraphs B. and C. of this AD.

E. An alternative method 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 forwarded through an FAA Principal Maintenance Inspector, who may concur or comment and then send it to the Manager, Standardization Branch, ANM-113.

F. 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 AB, Product Support, S-581.88, 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 39-7044 supersedes AD 90-16-02, Amendment 39-6676 which superseded AD 88-13-10, Amendment 39-5963.

This amendment (39-7044, AD 91-14-02) becomes effective on July 29, 1991.