Jim,

Please don't reply in such a way as to make it appear that I said something
that I did not. It was Matt Whiting that made the comment about losing all
engines on a twin being more likely than losing all four. I didn't say
that, and I know that is not true.

Dean
wrote in message
...
In rec.aviation.owning Dean Wilkinson wrote:

True, but the probability of losing all of the engines at the same
time
is greater with only two engines as opposed to four.

Matt

Not necessarily...

There has never been a historical case of a twin engine jetliner
losing both engines at once due to unrelated failures. All twin
engine failures have been due to a common cause; fuel starvation being
the prime reason.

Here are some examples of related engine failures:

A four engine 747 had all four engines flame out at the same time when
it flew into the ash cloud of Mt. Redoubt in Alaska, and only managed
to restart three of them after losing over 10,000 feet of altitude.

A four engine Airbus A340 made a dead-stick landing at Lajes in the
Azores after running of fuel due to a combination fuel leak and fuel
system management problem.

A 767 (twin) made an emergency landing in Canada on a drag strip after
losing both engines due to a miscalculation during fueling.

The probability of an ETOPS plane losing both engines in a single
flight due to unrelated failures is extremely remote. That doesn't
mean it can never happen, but it is less likely than winning the
lottery.

Not quite; the probability of all engines failing decreases with the
number of engines if all engines have the same probability of failing.

Whether or not this will actually happen is highly dependent on the
probability of the individual engine failing.

Since airline engines tend to be well maintained, and hence the probablity
of failure low, one could reasonably say the chances of multiple engine
failures (no common cause) is quite remote.

However, a friend of mine that spent lots of time in B-52s relates the
tale of the time they lost 3 engines (no common cause) during flight
and a fourth engine on final getting "that big piece of crap" back on
the ground.

--
Jim Pennino

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