Originally Posted by
Musician
I'm fairly certain that @tdracer simply misremembered the country, because the details fit, and the Saudi event is referenced everywhere while the Egyptian event is not (and its details don't fit).
There are several assumptions here that are not warranted, "qualified professional" first and foremost
"It was recently observed" does not imply an event; it could be a study like "
Research on Risk Assessment with Uncontrollable High Thrust for Civil Airplane" (but not this exact one as it came out later). As far as I could ascertain, the Saudi event occurred in 1997, the NTSB issued a recommendation in 1998 (also quoted by me, albeit hidden by spoiler), and the FAA then started to enforce the existing "single point of failure" regulations with regard to UHT for type certifications from some point on forward, which led to the aircraft manufacturers requesting these exemptions. I don't have an exact timeline on that.
I can confirm that the Saudi event is the one that started this whole UHT mess (not sure why my memory had an Egyptian connection, but at least I had the correct region of the world
).
The FAA was a little startled when we told them that if they were going to hold to that strict 25.901(c) interpretation, we'd never be able to show compliance to that regulation for future improvements to the engine fuel control systems - even those that were specifically intended to address UHT causes. So Boeing had to request the partial exemption for all aircraft models - which was quickly adopted. Unintended consequences at work.
At some point in the future, I was working a new FADEC s/w cert for a 767/747-400 engine when it was determined that the exemption had not been FAA approved for one of those aircraft models (I don't remember now if it was the 767 or 747-400 - I think it was the 767 but don't hold me to that). I quickly raised this problem with the FAA, and the exemption was extended within days.