"Darkwing" theducksmail"AT"yahoo.com wrote in message
...

I'm assuming that turbos on planes have a popoff boost valve. Ever had
those
checked to make sure they hold pressure properly? Maybe they are getting
hot
and losing their resistance.

Thanks - I can't say for certain whether that has been considered or checked
at this point. We have mainly suspected that there is some coking despite
being careful about allowing proper spin down time.

BDS