COMMONWEALTH OF AUSTRALIA (Civil Aviation Regulations 1998), PART 39 - 106 CIVIL AVIATION SAFETY AUTHORITY
SCHEDULE OF AIRWORTHINESS DIRECTIVES
Allison Turbine Engines - 250 Series
AD/AL 250/55
Amdt 3
Gas Producer Rotor Assembly - Tie Bolt P/N 6843388, 6876991 and 6889320
4/89
Applicability: All Models 250 - C18, - C18A, - C18B and - C18C 250 - C20, - C20B, - C20F, C20J and - C20S 250 - B15G 250 - B17, - B17B, - B17C, B17D and B17E 250 - C28B, -
C28C 250 - C30, - C30P and - C30S turbines whose serial numbers are advised in the Requirement Document and, any other turbine assy which has turbine tie bolts Part Number 6843388, 6876991 or 6889320 fitted.
Requirement: Remove from service
(i) tiebolts P/N 6843388, and
(ii) tiebolts P/N 6876991 and 6889320
in accordance with:- |
| ||
Allison 250 | - C18 | CEB - 234 | Revision 2 |
| - C20 | CEB - 1212 | Revision 2 |
| - B15G | TP CEB - 104 | Revision 2 |
| - B17 | TP CEB - 1173 | Revision 2 |
| - C28 | CEB - 72 - 2093 | Revision 2 |
| - C30 | CEB - 72 - 3109 | Revision 2 |
Compliance: Unless already accomplished, For Part (i)At the next turbine repair or overhaul or by 28 February 1990 whichever is the sooner. For Part (ii)At the next turbine repair or overhaul or by 28 February 1992 whichever is the sooner.
Background: This directive is amended to reflect Revision 2 to the Requirement Documents which adds P/N 6843388 tie bolt assembly and a compliance schedule for its timely removal from service.
Compliance with this Directive will introduce new tie-bolts of improved strength to supersede tie-bolts which have experienced fatigue cracking in the threaded area.
Failure of the tie-bolt could result in G.P. rotor failure, leading to turbine wheel fragments leaving the engine with the potential to severely damage the aircraft.