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Firefly accident in North Yorkshire.

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Firefly accident in North Yorkshire.

Old 26th Jan 2018, 07:14
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I flew a T67A. A different aircraft in many ways to the T67M’s but the same horizontal/vertical tail configuration and additional rear CofG traps for the unwary. It seemed to me that if the aircraft flicked into an incipient spin, the natural reaction was to unload, ie, stick forward. It was then counter intuitive to first move the stick back, apply full then stick forward again. I also suspect that some accidents arose from slow centring of the controls and going into an inverted spin.
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Old 26th Jan 2018, 12:11
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Originally Posted by robrob View Post
Luck.

Seriously, read the "UK Fatal Stall or Spin Accident Summary (1980-2008) report".

It's not a good idea to let low experience aerobatic pilots fly the Firefly without a really good spin checkout. Even then I wouldn't let a friend train in the Firefly.
Luck? The often Gary Player credited quote comes to mind about luck which you seem to realise with your own view on practice being a good idea. The pilots in the Yorkshire event sadly didn't seem to.
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Old 26th Jan 2018, 16:08
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Pitts, the "Luck" response was in response to this question:

how is it that the aircraft is used by new/novice/inexperienced aerobatic pilots without incident?
This implies inadequate practice.

rotorfossil, I don't know if it's in the civilian Firefly flight manual but the USAF had a T-3A "Spin Prevent" procedure which did exactly as you said. We would do a normal spin entry (idle, nose up, full rudder) and when the spin began we would unload with forward stick and apply opposite spin rudder and stop the spin in less than one turn. If that didn't work we were to transition to the full up "Spin Recovery" procedure. It was extremely rare for the spin prevent procedure to not work--it never happened to me and I did hundreds of them.
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Old 27th Jan 2018, 07:18
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Robrob. Unfortunately Iíve thrown away my old T67A POH copy but I donít remember it mentioned anything other than the standard full opposite rudder/move stick forward technique. Because of the long wings, I suspect that inadvertent outspin aileron might have have been another factor in delayed spin recovery.
The T67A was a nice aircraft for gentle aerobatics but it was frightenly easy to operate it outside the rear Cof G limits and I suspect that they often were. The low max AUW meant that the fuel load had to be limited for Aeros two up. As the fuel tank is forward of the cockpit this moved the cg aft. The cockpit seats were on rails so two 170 lb people with long legs really shifted the C of G back. In the end it was necessary to have a complex table of fuel load/ crew weights/ seat positions for the group members (not highlighted in the POH). The result was that I ( 190 lbs long legs) could fly with my wife (small light person) but nobody else in the group.
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Old 27th Jan 2018, 15:15
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Some (most?) Fireflies (B, C, M) have fixed seat and moveable rudder pedals, perhaps for that reason?
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Old 27th Jan 2018, 15:31
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The T-3A had fixed seats and adjustable rudder pedals.

As I mentioned earlier, when I measured the CG in a T-3A with full fuel, me and a large cadet + parachutes and canopy closed it was 2 inches rear of the limit. This was done without leveling the aircraft because our squadron didn't yet have the Firefly leveling tool but it was done on a known level hangar floor.
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Old 12th Feb 2018, 19:00
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robrob - do you recall the calculated CG position, W&B wise?
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Old 12th Feb 2018, 20:55
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No, I don't remember the specific number but we came out right at 2 inches rear of the rear limit. If I recall correctly the firewall was the datum line.

It's possible this is one of the reasons the Air Force chopped up the T-3A fleet. They discovered the problem and didn't want to open the can of worms of trying to explain why we flew the aircraft for 3+ years with it out of specs.
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Old 13th Feb 2018, 21:57
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Inverted Spinning by accident

One thing that concerns me with spinning, is the amount of people that tell me that they 'fell into' an inverted spin. Whilst indeed it is possible to do, I have personally witnessed many pilots telling me that is what happened to them, when it was actually only an incipient erect spin. They seem to think that just because the aircraft briefly rolled inverted, that it was therefore an inverted spin. If they then try to recover with backstick, then they are in for a shock.

Such confusion helps explain why some people fail to recover from various spins - they don't properly identify the type of spin they are in. An inverted spin has a negative G pitching moment (ie seat belts floating in front of your face), yaw in the direction of spin, and rolling in the opposite direction. That in itself can cause massive confusion.

Such a shame that the majority of pilots don't experience both types of spins, with an aerobatic instructor.
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Old 14th Feb 2018, 07:19
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Because of possible confusion between erect and inverted spinning, all aerobatic aircraft should have a turn and slip NOT a turn coordinator. Roll in the same direction as turn needle - erect spin, normal recovery action. Roll in opposition to turn needle - full rudder in opposition to turn needle, pause, stick back.
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Old 23rd Feb 2018, 21:50
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firefly

I have operated T67M aircraft from 1996 to now. 160, 200 and 260
I competed in aerobatic competitions in firefly's. I have displayed firefly's
I have coached a large number of pilots to fly aerobatics in the firefly mainly for competition. Their experience varied from 100 hours ppl to 8000 hour ATPL.
Before solo flight they all were capably of
  • Entry to positive spin ( not a flicked entry) hold and count six turns and clean recovery
  • Entry to and recovery from power on flat spin
  • Recovery from to normal flight from power on departures initiated by me. This being a flick roll into high rotational spin on a number of lines, i.e. vertical, down 45 degree dive, climbing 45 degree line and top of the loop
  • Demonstrate precision competition spins of one, one and a quarter, and one and a half turn in either direction.
  • Fly a sportmen's (standard level) aerobatic program within an aerobatic performance zone ( kilometre square) staying within hight, G and speed limits
This takes time, a lot more time than the 5 hours plus "aerobatic rating" Not all the pilots manage to achieve the level, the ones that don't don't go solo. We have done north of 5000 hours aerobatics without incident.

The firefly is a wonderful training aeroplane. It teaches effects of controls in all phases of flight. Having mastered spinning the firefly a pilot will be in a much better position to recover any light aircraft from a spin. The firefly does not recovery from a spin if the stick is released and opposite rudder is applied (Beggs) It just changes the direction of rotation. The Pitts type is one of the few that recovers using that sort of technic.

.
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Old 24th Feb 2018, 11:40
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That's very rigorous aerobatic training and what's needed in the Firefly.
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Old 24th Feb 2018, 12:07
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I train pilots on Extra aircraft as well and the same rules apply
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