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-   -   A109 Emergency AD. (https://www.pprune.org/rotorheads/363009-a109-emergency-ad.html)

HeliCraig 20th February 2009 12:13
A109 Emergency AD.
 
Chaps (& Chapesses),

EASA have published an Emergency AD for the A109 yesterday, effective on particular RR engines; which creates a new operational limitation.

Following several third stage turbine wheel failures, the engine Type
Certificate holder, Rolls-Royce Corporation, issued Commercial Engine
Bulletin (CEB) A-1400 Rev. 3 to introduce an operational limitation on the
power turbine N2 speed range (95% - 97%) for more than 60 seconds in
single or cumulative events for engines with the third stage turbine wheel
P/N 23065833 installed.

Thereafter, Agusta issued Bollettino Tecnico (BT) 109-129 to introduce the
same operating limitation, which is also required by this AD, on the affected
helicopters.
Not being a turbine driver (yet), I have a question: Does this mean you can operate above 97% for >60s; or is that already a limitation?

Will this AD cause anyone any real heartache?

spinwing 20th February 2009 12:28
Mmmm ....

No ... as I read it it means you must not operate between 95-97 % N2 (Nr).

Operations above 97.1% should remain as per normal.

Probably to do with some form of vibratory resonance 'twixt 95 & 97% N2 speeds.

:E

HeliCraig 20th February 2009 12:31
Sorry - meant to say that a copy of the AD is available here.


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