Crash analysis

[graeme jones]

Has anyone ever analysed the reasons for our crashes with a view to prevention? This is always done in full size aviation but I've never seen anyone do it for models. I'll start with a description of my last crash. If there is already someone collating these then please let me know and add this one in. If not I would welcome your crash/near miss stories and will let everyone know what if anything I learn from them.

 

Date 14/10/10. Location Marshfield South Wales. Weather cold calm overcast. I was flying my ASM P61 Black Widow with a pair of OS48FS's. Because there was no wind I had to abort the first takeoff due to a lack of airspeed. Back to the pits to restart the motors and lean them out slightly for more power (the more experienced of you will see where this is going). Takeoff now OK, did a couple of (left hand) circuits and some gentle aerobatics, a loop and a roll. Now lets try a pass down the runway. Full power, nose down, aircraft passes me at about 50 feet altitude. Port motor stops. Aircraft is too high and too fast to cut starboard motor and land straight ahead, but is too low to cut motor and turn (left) back to the runway. Only option now is to keep the starboard motor at full power and turn RIGHT, i.e. against the good motor. This might have worked except that the approach would have been in the dead airspace over the clubhouse and pits. So I tried to turn left, at which point the aircraft spun and crashed in the adjacent field. It was a safe crash in that it was 200 yards away from anything, but it did take 3 people to pick up the bits. Root cause of crash? Overconfidence on the part of the pilot. What did the pilot learn? He's not infallible and it's only a hobby!

[Steve W-O]

If your going to analyse it how about some questions about different procedures.

 

If you had cut the other motor and landed straight ahead, would there have been less pieces to pick up?

 

Would a gentler turn have prevented the spin?

 

Would keeping the rudder in to correct the one sided thrust, and a gentle turn on ailerons have worked?

 

Would turning on reduced throttle and opening it in straight flight to gain/maintain height have helped?

 

Were the motors too small in the first place?

 

Was the plane correctly trimmed before take off?

 

Was it really overconfidence, or incorrect motor adjustment?

[GrahamC]

Ouch!

Never had a twin, though I have an own design Wellington slowly coming together from foam in the shed.

 

Having seen a few videos on YouTube of similar happenings makes me realise how vulnerable and airframe is when one engine fails. Makes the case for electric twins strong!

 

Interesting isn't it how dead sticks seem to happen mainly in bad places?

 

My last one was at 30 feet over the boundary hedge just after taking off. Fortunately it was the Wot 4 and I got away with it. I don't think I would have with any other models in my hanger!

 

[Ernie]

Hi guys, I've been doing this for a while now. Problem is that it needs to be done over a considerable amount of trime to be relevant

 

ernie

[graeme jones]

To Steve W-O - if I had cut the starboard motor and flown straight ahead the aircraft would have been over the boundary hedge, across a lane and into the club's designated dead airspace. Yes other possibilities existed, but with only seconds to react none of them sprang to mind. I did the safest thing possible under the circumstances. At the other (private) site which I use I would simply have continued to turn right, since we don't have any designated dead space and there is nothing to hit. In any case I'm not looking for suggestions of how the crash could have been avoided, I'm trying to find out if it is worth analysing crashes to prevent some in the future. The root cause of mine was overconfidence that a couple of clicks lean would be OK. I always use a tacho when flying twins and this aircraft had experienced two dead stick landings before, but each time I had sufficient height to regain the runway.