AIRWORTHINESS DIRECTIVE

For the reasons set out in the background section, the CASA delegate whose signature appears below issues the following Airworthiness Directive (AD) under subregulation 39.1 (1) of CASR 1998. The AD requires that the action set out in the requirement section (being action that the delegate considers necessary to correct the unsafe condition) be taken in relation to the aircraft or aeronautical product mentioned in the applicability section: (a) in the circumstances mentioned in the requirement section; and (b) in accordance with the instructions set out in the requirement section; and (c) at the time mentioned in the compliance section.

General Electric Turbine Engines - CT7 Series

AD/CT7/9 Compressor Variable Geometry Schedule 6/2003

TX

Applicability: All CT7-9B engines.

Note 1: These engines are known to be installed on but not limited to SAAB Aircraft 340B aeroplanes.

Requirement: 1. Determine the Variable Geometry (VG) rigging schedule for both engines. If the compressor VGs are rigged to VG schedule N using GEAE Service Bulletin (SB) CT7-TP S/B 72-0328 or GEAE Alert Service Bulletin (ASB) CT7-TP S/B 72- A0328 Revision 1 no further action is required.

Note 2: The engines with Serial Numbers (S/Ns) listed in Table 1 of this directive are known to have been rigged to VG schedule N1.

2.        If the compressor VGs on both engines on the aeroplane are rigged to VG schedule N1, accomplish the following:

1. rig the compressor VG on one engine to VG schedule N in accordance with 3.A.(1) through 3.A.(12) of the Accomplishment instructions of GEAE ASB No. CT7-TP S/B 72-A0328 Revision 1; and
2. rig the compressor VG on the remaining engine to VG schedule N in accordance with 3.A.(1) through 3.A.(12) of the Accomplishment instructions of GEAE ASB No. CT7-TP S/B 72-A0328 Revision 1.

3.        If the compressor VG on one engine on the aeroplane is rigged to VG schedule N1, rig the engine to the VG schedule N in accordance with 3.A.(1) through 3.A.(12) of the Accomplishment instructions of GEAE (ASB) No. CT7-TP S/B 72-A0328 Revision 1.

4.        Do not install any GE CT7-9B engine rigged to VG schedule N1 on a SAAB Aircraft AB 340B aircraft.

Table 1 S/N’s of Engines Known to Have Been Rigged to VG Schedule N1.

Note 3: FAA Emergency AD 2003-08-52 refers.

Compliance: 1. Within 30 flight hours or 3 days from the effective date of this directive. 2a. Within 30 flight hours or 3 days from the effective date of this directive,

whichever is the later.

2b. Within 100 flight hours or 10 days from the effective date of this directive, whichever occurs first.

3.        Within 100 flight hours or 10 days from the effective date of this directive, whichever occurs first.

4.        From the effective date of this directive.

This Airworthiness Directive becomes effective on 17 April 2003.

Background: This directive is in response to 12 stall events that occurred over a 6- month period. It has been determined that in the majority of the stall events the VG was rigged to the N1 schedule. Re-rigging the VG to the N schedule will give a highe r stall margin. If the VG schedule is not adjusted to the N schedule the aircraft could suffer a dual inflight shutdown or power loss during deceleration from take off power to climb power.

David Villiers

Delegate of the Civil Aviation Safety Authority 16 April 2003

The above AD is notified in the Commonwealth of Australia Gazette on 17 April 2003.