[<anon>: A310 EROPS]

From:         Robert Dorsett <rdd@netcom.com>
Date:         09 Jul 96 13:09:39 
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A310 with P&W engines loses EROPS qualification.

After suffering a second engine failure en route this year on Sunday, June
30, A310s with P&W engines lost their EROPS qualification in Belgium. Fewer
than 25 of A310s produced share the engine configuration involved. The
problems are traced back to a failure of the forward bearing of the engine.

On the A310, part of the engine nacelle is stressed to support the engine.
This allowed for lighter engine / wing mountings, saving weight in the
process. However, if the nacelle is not correctly aligned, extra stress is
placed on the forward engine bearing, causing it to fail prematurely.

As a result, the authorities lowered the time to replace the bearing from
10,000 hours to 6,000 hours. However, the bearing on the failed engine
last sunday had fewer than 400 hours on it.

The statistics for *in flight shut down* for the complete fleet of A310s
with P&W engines still meet EROPS criteria. The statistics for the decision
to withdraw the qualification are based on fewer than 20% of the world wide

EROPS qualifications are sometimes *partially* based on experience of the
engine on another airframe. The same P&W engine on other airframes has a
much better *in flight shut down* rate, likely because these airframes do
not use the concept of the stressed nacelle.

GE engines on the same A310 also have a much better reliability.

Apparently, the engine/airframe combination causes unwanted interference
leading to the higher *in flight shut down* rate on the A310/P&W combination.

Robert Dorsett                         Moderator, sci.aeronautics.simulation
rdd@netcom.com                         aero-simulation@wilbur.pr.erau.edu