AIRWORTHINESS DIRECTIVE
CAA-AD-4-085/98
Supersede CAA-AD-4-071/97
Date of issue: November 26, 1998
AIRCRAFT - HORIZONTAL STABILIZERS - COLD WORKING EXPANSION PROCEDURE
Applicability: SAAB SF 340A -004 through -159 and SAAB 340B -160 through -439
Effective date: December 31, 1998
Compliance:
Required as indicated in SAD AD č. 1-133.Remarks: Where applicable, the requirements of this AD must be integrated into the Aircraft's Logbook(s). Address inquiries concerning this AD to: Civil Aviation Authority, Airworthiness Division, Ruzyně Airport, 160 08 Prague 6, Czech Republic, tel.: 420
2 324086, fax: 420 2 364112.Ing. Pavel MATOUŠEK
Director of Airworthiness Division, CAA CZ
LUFTFARTSVERKET Aviation Safety Department SWEDISH AIRWORTHINESS DIRECTIVES (SAD) SAD No 1-133
Section 1. Swedish Manufactured Aeronautical Products
AIRWORTHINESS DIRECTIVE NO: 1-133
AIRCRAFT TYPE: SAAB SF 340A and SAAB 340B
SERIAL No’s AFFECTED: SAAB SF 340A -004 through -159 and SAAB 340B -160 through -439
SUBJECT: Stabilizers - Horizontal Stabilizers - Cold expansion of holes in front spar of horizontal stabilizers
BACKGROUND: During "Full Scale Fatigue Test" fatigue cracks have been observed in the forward spar of the horizontal stabilizer. The observed cracks are located at the intersection between the rear fuselage and the forward upper spar cap. Starting point for the initial crack is considered to be in the upper part of the web at one of the fastener holes.
Propagation of cracks may ultimately result in a failure of the forward spar.
SAD 1-110R1 was issued to require certain inspections in order to ascertain continued airworthiness. It was also noted that a Mandatory Service Bulletin would be released describing actions to improve the fatigue life.
These actions have now been defined and calls out a Cold Working Expansion Procedure for four of the holes in the upper cap and the web. This procedure will extend the fatigue life and minimize future need for repairs.
REFERENCE DOCUMENTS: Saab Aircraft AB Mandatory Service Bulletin SAAB 340-55-34 dated 16 October 1998
ACTIONS: Perform actions described in Saab Aircraft AB Mandatory Service Bull‚tin SAAB 340-55-34 dated 16 October,1998 or later revision.
COMPLIANCE TIME:
For A/C with 0 - 26000 flights, to be performed within 10000 flights from release date of this SAD.
For A/C with 26000 - 30000 flights, to be performed within 6000 flights from release date of this SAD.
For A/C with 30000 flights or more, to be performed within 3000 flights from release date of this SAD.
Note: Implementation of this SAD supersedes action according to the Swedish Airworthiness Directive 1-110R1.
EFFECTIVE DATE: 20 October,1998