Greg,

 

I would like to hear some examples of "many rotary-driven aircraft had crashed".  I'm aware of one crash, but that was pilot error (flew into the trees while landing at night at an unlit airport).  The engine was undamaged. 

 

I also know of a few forced/precautionary landings.  One that comes to mind was due to the engine ingesting a 1/4" bolt.  This took out one rotor, but the other rotor kept producing power, just not enough to continue on straight and level flight.  This resulted in a precautionary landing on a road. 

 

I also remember a deadstick landing, but that was due to fuel starvation.  He fixed the fuel problem and flew the a/c home.  The flop tube got lodged above the level of the fuel in that tank.  No, he didn't try the other tank.

 

Then there was a forced landing due to a burst oil cooler.  The builder had used an a/c evaporator core as an oil cooler.  Needless to say, it failed after a few hours. 

 

And there were some turbo failures, as I have mentioned before.  The rotary engine was not damaged and safe flight continued on to the destination airport. 

 

I only know of one forced landing that was directly due to the engine.  In this case was due to the person that rebuilt the engine.  A piece of one of the apex seals (3-piece seals) fell out of place during assembly of the engine without the mechanic noticing.  It was caught and pinched between the rotor and side housing.  He thought that the engine seemed a bit tight, but went ahead and flew it anyway.  Needless to say, the engine tried to sieze (but never actually did) and he made an emergency landing.  This type of failure was not the fault of the engine, but rather the mechanic.  

 

I also recall (sadly) a friend that was killed in his rotary-powered Speed Queen.  That was determined to be the fault of the fuel system, not the engine.  He had been trouble-shooting his fuel system problem from the start.  He had even made one prior emergency (engine out) landing prior to his final flight.  As I recall, the cause was determined by the FAA to be due to his removing the oil injection pump.  That is total nonsense.  Many rotary-powered a/c have the oil injection pumps removed.  We choose to pre-mix the oil in the fuel instead of drawing sump oil via the oil injection pump.  It doesn't hurt the engine unless you forget to add oil when refueling.  Then it is a very gradual loss of power, not immediate engine seizure as you would see with a 2-stroke engine.  

 

So, its as they say... the devil's in the details.  

 

If you have actual (verifiable) examples of where the rotary engine failed in flight, causing a crash, I would sure like to hear about them.  But please provide some details so I know which accident you're referring.

 

 

Mark S.  

 

 

On 6/8/07, kneaded pleasures <kneadedpleasures@sbcglobal.net> wrote:

Mark Steitle writes, "....  As for the basic rotary engine, I feel that it is way more reliable than its certified counterparts." 

 

Perhaps true Mark, but isn't it also true that the most frequent failures of the rotary application to aircraft is the prsu?  In my not-so-recent readings on this topic, many rotary-driven aircraft had crashed and very few flying rotary a/c had significant hours on the engines and aircraft.  Is this still true?  How many flying hours do high-time rotary aircraft now see without major overhaul of either/both the engine and prsu?       Greg Nelson