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Old 22nd Feb 2006, 02:07
  #87 (permalink)  
Flight Safety
 
Join Date: Jan 2001
Location: Dallas, TX USA
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In a brief search of the Internet I didn't find any good engine restart statistics, and I wish I had them to back up this discussion, but I really want to elaborate on what Broadreach said:

What one thought was the basic airmanship learned in unreliable machinery over hostile terrain: always have half an eye out for some place to put the thing down and get out intact.
Truly when all engines shutdown (whether a single, dual, tri, or quad) at any significant altitude, basic airmanship must be:
  1. secure O2 if needed
  2. start a glide to a landing
  3. try a restart
If you can glide to a landing with all engines out, your odds of survival are good. If you can get a successful engine restart, your odds of survival are even better.

Again engine restart stats would be helpful here, but I think it's fair to assume that when all engines shutdown, the odds of a successful restart are generally fair, but I'd think they are less than 50 percent. I also think it's fair to assume that if you do get an engine restart, that the odds of having full power are less than 50 percent (either less than all engines, or less than full power from any engine, including a single).

The reasons I think the odds would fall somewhere in these ranges, has to do with the common reasons for all engines shutting down. Some of these are:
  • Icing
  • Fuel exhaustion
  • Fuel contamination
  • Fuel transfer problem
  • FOD damage (large volumes of water, ice ingestion, hail, ash, etc.)
  • Airflow disruption (maneuvering error, etc)
  • Maintenance error (that is common to all engines)
  • Pilot procedure error
  • Engine overtemp
  • Other reasons
Some of these reasons will not even allow an engine restart, and others will not allow full power after a restart. Only healthy engines, good fuel, and good fuel transfer will allow full power after a restart. In this accident we had 2 of these reasons present, airflow disruption and engine overtemp. At best, maybe the left engine could have been restarted, however this accident might have another reason for a restart failure, "core lock".

I really think that the odds are perhaps 1-in-4 (and maybe less) that you can regain full power after an all engine shutdown. Therefore I think the above basic procedure is paramount to your survival, should you suffer an all engine shutdown at altitude.
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