Here this TBM stall/spin accident came up.
However, as with most “modern” single engine designs, the TBM is supposed to be highly spin resistant. Twins are probably much easier to spin e.g. this one. But how much would it take to get a TBM into a spin, probably a flat spin, and hold it there all the way down from 20,000 feet?
You have to stall the plane first, which is easy. But then how much rudder input does a TBM need?
That BEA reports reads like so many accident reports on small GA aircraft i.e. lapsed/nonexistent/unknown pilot paperwork (the insurance may not have paid out so there will have been an ongoing tragedy for the pilot’s family due to passenger claims), maintenance issues / lack of interest in maintenance, possibly poor piloting skills, etc, but it is unusual to read about that at this level in GA.
But how much would it take to get a TBM into a spin, probably a flat spin, and hold it there all the way down from 20,000 feet?
Unless approved for spins I think they only have to show recovery from an incipient spin, although the fact they have ventral strakes suggests more extensive spin testing took place. (With a drag chute)
In a high rotation flat spin recovery may require applying pro spin controls again, before undertaking recovery.
Even aircraft approved for spinning can go rogue. Babcock lost some T67 because the crew had to bail out when recovery was not accomplished at the bail out altitude. The instructors were required to demonstrate recovery from a high rotation flat spin once a year, and I believe started the exercise at 10,000 feet.
Even a benign Cessna 150/152 where letting go 99% of times leads to recovery in a dive, the spin can go rogue.
As previously stated, looking at the vertical altitude/speed profile of this TBM accident, there is a strong indication that a spiral dive was allowed to develop first (high-speed banking turns, descending). The proper recovery from a spiral dive is to level the wings while pushing the yoke hard forward to counteract the trim-speed seeking pitch-up force generated by the excess airspeed and airframe decalage.
Here is another TBM study by BEA:Loss of Control study
Here is the spin recovery required for certification Part 23, there are alternative menas of compliance, eg Cirrus.
Normal category airplanes. A single-engine, normal category airplane must be able to recover from a one-turn spin or a three-second spin, whichever takes longer, in not more than one additional turn after initiation of the first control action for recovery, or demonstrate compliance with the optional spin resistant requirements of this section.
(1) The following apply to one turn or three second spins:
(i) For both the flaps-retracted and flaps-extended conditions, the applicable airspeed limit and positive limit maneuvering load factor must not be exceeded;
(ii) No control forces or characteristic encountered during the spin or recovery may adversely affect prompt recovery;
(iii) It must be impossible to obtain unrecoverable spins with any use of the flight or engine power controls either at the entry into or during the spin; and
For an acrobatic aircraft they have to demonstrate a six turn spin, recovering in less than 1 1/2 turns.
The TBM as a normal category, spins prohibited, aircraft, would only have been certified to a one turn spin where auto rotation would not have stabilised. Once recovery was not accomplished after one turn the TBM may naturally go flat, but the BEA does not explore this. Spin entry was interesting with a 45 degree pitch up and may have been accelerated?
Even the most spin resistant aircraft will spin if it is yawing at the point of stall, although spin resistant aircraft like the Warrior achieve this in part by limiting stabilator travel so achieving critical AofA at 1g is not easy.
What was surprising in this BEA report is their description of standard stall recovery:
The actions to perform to recover from a stall, if it is correctly identified mean levelling the wings, pushing the control column forward to reduce the angle of attack and regaining speed.
SSR is relieve back pressure on the control column to eliminate symptoms, smoothly apply full power, and then, and only then, roll wings level. This is to avoid control roll reversal from the ailerons at the point of stall.
I am not sure I understand the last statement – relieve back pressure, apply full power and then roll wings-
in a spin the first thing to do is to reduce power either completely or as in the yak 55 keep some to maintain flow over the rudder, then stop the rotation with opposite rudder and recover, the plane will be on a dive and after generating enough speed then increase angle of attack and add power, not before
of course if this is done at 300 feet you have no chance to recover
please correct me
I regularly land my evolution with idle power and substantial higher altitude, really an overhead approach with turn close to the threshold to avoid having to raise the nose at any point on the landing, otherwise you will end up like all examples of the TBM with the deadly turn to runway stall and being short.
The comment relates to the BEA’s incorrect description of standard stall recovery, it was not related to spin recovery which is type specific.
Peter wrote:
You have to stall the plane first, which is easy. But then how much rudder input does a TBM need?
At demonstrations I’ve seen, it would lower the nose when stalled. No sudden wing drop.
My understanding of the linked accident is that the pilot was in IMC and once the aircraft was spinning, may have used counter spin aileron. This results in flattening the spin, not recovery. Another thing he may have done is applying power, which makes the spin even flatter, as the gyroscopic effect brings the nose up. So there you have it, counter spin aileron and full power – untrained pilot in IMC could see them as recovery techniques, while an aerobatic pilot uses them to do nice flat spins.
