CAF Dakota crash, Burnet, TX 21-7-18
As far back as 1948 several DC 3 accidents and incidents had been attributed to the Sperry A 3 autopilot.
So much so that at least one leading airline removed their autopilots.
Problems encountered included:
Operating stop of follow up cable fouling controls
Cable detached fouling controls
Pulley seized
Cable return spring broken.
Some operators were in the habit of engaging the autopilot on turnarounds as a 'quickie' gust lock. I even encountered one Brit pilot who engaged it while taxying in extreme winds, such as we often encountered in the Shetlands. Baaad idea.
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So much so that at least one leading airline removed their autopilots.
Problems encountered included:
Operating stop of follow up cable fouling controls
Cable detached fouling controls
Pulley seized
Cable return spring broken.
Some operators were in the habit of engaging the autopilot on turnarounds as a 'quickie' gust lock. I even encountered one Brit pilot who engaged it while taxying in extreme winds, such as we often encountered in the Shetlands. Baaad idea.
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The reaction of the verbally challenged observer in that vid indicates that something major was going wrong early on in the t/o run that isn't so obvious on film. In slo-mo it is clear there are large and long rudder inputs from the very start of the t/o run while the tailwheel is still on the ground and I get the feeling that the tail was lifted somewhat abruptly - so posssibly early - as though he really wanted it off the ground and quickly. Slo-mo also reveals changes in aspect of the wings which shows a major weave developed early on as evicenced by the soundtrack. Why then? Is the tailwheel is locked or not for t/o? What happens if the selection is the wrong one? Can it lock off-centre if you don't taxi forward a little after entering the runway? Might any of that explain the swing/pio he got into?
Last edited by meleagertoo; 22nd Jul 2018 at 09:37.
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3000hrs+ on DC3’s. Immediate thought...pilot error. The procedure on any normal DC3 take-off requires the tail to be raised, there is no take-off procedure that calls for the tail to held as it was. Yes pre-take-off check are tailwheel locked.
Next, was the possibility of massive unintended overloading in the tail. Unlikely, but if the tail was not coming up as it should something is badly wrong...abort!.
Next was inadvertent autopilot engagement? The minute the pilot realises he cannot apply for ward yoke and raise the nose, he should abort the take-off.
The investigation will no doubt reveal what happened.
Next, was the possibility of massive unintended overloading in the tail. Unlikely, but if the tail was not coming up as it should something is badly wrong...abort!.
Next was inadvertent autopilot engagement? The minute the pilot realises he cannot apply for ward yoke and raise the nose, he should abort the take-off.
The investigation will no doubt reveal what happened.
It does mot take much to shear the tailwheel lock pin. In light winds it is not really needed. In strong crosswinds, yes, until the rudder becomes effective it is most helpful, but I dare say a skilled pilot could probably manage without it. Unless it was blowing hard, unlikely primary cause.
I see a lot of relevant stuff has been posted since yesterday. I don't recall ever doing a full-power stall during my (mere) 500 hrs P2 on the Dak (C47), so am interested to read the comments of Centaurus and Mach e Avelli. There seems no doubt that the a/c got airborne in a stalled or incipiently-stalled condition, left-wing first, and with a lot of power on. Was the power symmetric? Probably.
A couple of posters have commented on the first exclamation from the camera operator early in the take-off run. A closer look confirms that the swing to the left was a lot more pronounced than I first thought. Yes, the tail-wheel lock might not have been engaged, and we have as yet no report of the W/V. Or there might have been a loss of power on the left engine. But if so, why was the take-off not abandoned? Having continued, why was the tail-wheel lifted and then grounded again until main-gear lift-off?
Too many unanswered questions...
A couple of posters have commented on the first exclamation from the camera operator early in the take-off run. A closer look confirms that the swing to the left was a lot more pronounced than I first thought. Yes, the tail-wheel lock might not have been engaged, and we have as yet no report of the W/V. Or there might have been a loss of power on the left engine. But if so, why was the take-off not abandoned? Having continued, why was the tail-wheel lifted and then grounded again until main-gear lift-off?
Too many unanswered questions...
In the TV footage shown here tonight, the port propeller did not show any signs of hitting the ground under power whereas the starboard propeller was separated from the engine and bent as though it had bit the ground with a lot of power being delivered.
CNN
CNN
Last edited by 601; 22nd Jul 2018 at 13:00.
Tailwheel will only lock in the trailing position. You release the lock under the throttle quadrant (it's spring loaded to the lock position) and as the tail wheel centers an arm drops over the centering pin.
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My limited time flying the turbine DC-3 was largely exploring stall characteristics, and slow speed handling. I experienced a number of sudden left wing drops during the stall testing, as well as pitch control forces at very slow speeds less common compared to those of modern aircraft. The ailerons are large, and if deflected much during the approach to stall, will increase drag, and cause a more aggressive wing drop. This pilot appears to have been in the awkward situation that the aircraft was airborne in an nose high attitude which probably prevented acceleration to a safe flying speed, and was too nose high to allow a return to the runway for a normal landing/abort. As roll occurred, there would be a temptation to level the wings with aileron, which would worsen the situation. Yes, the tail should be well up during the mid takeoff roll. The rudder is plenty effective to maintain heading, the tailwheel lock is no longer needed at speeds at which the tail can be lifted.
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Some information on the C-47 from the Commemorative Air Force website:
(Burnet, Texas, July 21, 2018) - This morning a little after 9 a.m. Central, the Commemorative Air Force’s World War II aircraft, C-47 Bluebonnet Belle N47HL, had an accident at takeoff and caught fire. The accident occurred at Burnet Municipal Airport in Burnet, Texas where it is assigned to the Highland Lakes Squadron. There were 13 people on board the aircraft when the accident occurred. All 13 were able to exit the aircraft without any fatalities. A few suffered injuries and two are currently being treated at hospitals. The fire was extensive, and the aircraft is a total loss. The cause of the accident is currently unknown. The CAF is in direct contact with the National Transportation Safety Board (NTSB) and the Federal Aviation Administration (FAA) to support an investigation into this accident. “We are thankful the aircrew was able to exit the aircraft. Out hearts go out to them and their families as they recover,” said CAF President Bob Stenevik. “Unfortunately, the historic aircraft will not be able to be restored. Our volunteer members work very hard to keep these aircraft flying and it is a loss for the entire organization.”
About C-47 Bluebonnet Belle: The C-47 Bluebonnet Belle is assigned to the Highland Lakes Squadron based in Burnet, Texas. This C-47 was built in Oklahoma City in late 1944 and transferred to Great Britain under the Lend Lease Act of 1941. The RAF aircraft was ferried to RAF Kemble in southwest England, to the No. 48 Squadron, 46 Group, RAF Transport Command to replace losses sustained by 48 Squadron in the Normandy invasion in June 1944 and Operation Market Garden. Throughout the Normandy battle, 46 Group ran a daily shuttle service between England and France, its aircraft flying in cargo and passengers and evacuating casualties, saving thousands of lives by transporting wounded to hospitals. In total, Bluebonnet Belle flew 75 missions, carried 402 passengers, repatriated 61 ex-POWs, and transported 459 casualties before the stand down. In 2017, CAF volunteers joined Hurricane Harvey relief efforts by loading up the historic transport aircraft Bluebonnet Belle to deliver food and supplies to cities in Southeast Texas affected by the storm.
https://commemorativeairforce.org/aircraft/155
Commemorative Air Force Confirms Accident with WWII Aircraft C-47 Bluebonnet Belle
(Burnet, Texas, July 21, 2018) - This morning a little after 9 a.m. Central, the Commemorative Air Force’s World War II aircraft, C-47 Bluebonnet Belle N47HL, had an accident at takeoff and caught fire. The accident occurred at Burnet Municipal Airport in Burnet, Texas where it is assigned to the Highland Lakes Squadron. There were 13 people on board the aircraft when the accident occurred. All 13 were able to exit the aircraft without any fatalities. A few suffered injuries and two are currently being treated at hospitals. The fire was extensive, and the aircraft is a total loss. The cause of the accident is currently unknown. The CAF is in direct contact with the National Transportation Safety Board (NTSB) and the Federal Aviation Administration (FAA) to support an investigation into this accident. “We are thankful the aircrew was able to exit the aircraft. Out hearts go out to them and their families as they recover,” said CAF President Bob Stenevik. “Unfortunately, the historic aircraft will not be able to be restored. Our volunteer members work very hard to keep these aircraft flying and it is a loss for the entire organization.”
About C-47 Bluebonnet Belle: The C-47 Bluebonnet Belle is assigned to the Highland Lakes Squadron based in Burnet, Texas. This C-47 was built in Oklahoma City in late 1944 and transferred to Great Britain under the Lend Lease Act of 1941. The RAF aircraft was ferried to RAF Kemble in southwest England, to the No. 48 Squadron, 46 Group, RAF Transport Command to replace losses sustained by 48 Squadron in the Normandy invasion in June 1944 and Operation Market Garden. Throughout the Normandy battle, 46 Group ran a daily shuttle service between England and France, its aircraft flying in cargo and passengers and evacuating casualties, saving thousands of lives by transporting wounded to hospitals. In total, Bluebonnet Belle flew 75 missions, carried 402 passengers, repatriated 61 ex-POWs, and transported 459 casualties before the stand down. In 2017, CAF volunteers joined Hurricane Harvey relief efforts by loading up the historic transport aircraft Bluebonnet Belle to deliver food and supplies to cities in Southeast Texas affected by the storm.
The C-47 "Bluebonnet Belle" on display in our hangar is owned by the Commemorative Air Force. It was built in Oklahoma City in late 1944 as a C-47B serial number 43-49942; then flown to Montreal, Canada where it was transferred to Great Britain under the Lend-Lease program. The aircraft was ferried to England and served with the RAF. In 1945 it was assigned to the No. 435 Transport Squadron, a Canadian unit as KN270. It was ferried to Canada in 1946. The aircraft received the Canadian Forces serial 12909 in 1970. It was surplussed and entered civilian service in 1974. From 1974 until 1995, the aircraft was owned by a number of Canadian airline and charter companies, after which it was repatriated to the USA.
The Highland Lakes Squadron purchased this aircraft from a Part 135 cargo operator and donated it to the CAF in 2002. While legally airworthy she was in need of a lot of tender loving care. It required a two-year restoration project by the Highland Lakes Squadron to bring the aircraft up to operational standards.
Named the “Bluebonnet Belle” in honor of her home base Burnet, Texas, the Bluebonnet Capital of Texas, she is flown by experienced crews and treats air show crowds to the roar of her two mighty Pratt and Whitney radial engines. She serves as a living memorial to the thousands of men and women who built, serviced and flew them during the war years.
The Highland Lakes Squadron purchased this aircraft from a Part 135 cargo operator and donated it to the CAF in 2002. While legally airworthy she was in need of a lot of tender loving care. It required a two-year restoration project by the Highland Lakes Squadron to bring the aircraft up to operational standards.
Named the “Bluebonnet Belle” in honor of her home base Burnet, Texas, the Bluebonnet Capital of Texas, she is flown by experienced crews and treats air show crowds to the roar of her two mighty Pratt and Whitney radial engines. She serves as a living memorial to the thousands of men and women who built, serviced and flew them during the war years.
https://commemorativeairforce.org/aircraft/155
Good news that, to infer from the operator's statement, the two detained in hospital are in reasonable shape.
I guess that the pre-mod tendency of the stall to propagate from the wing-tips inwards in the power-on case is because the inner-wing airflow is smoothed by the propellor slipstream? But that's not to suggest that the mod results in a benign stall with power on. Is there any wash-out of the rigger's angle between root and tip? I never noticed any.
FWIW, however, here's the single paragraph describing the stall characteristics of the C-47, taken from the UK Air Ministry's Pilot's Notes for the Dakota 4, published in 1946 (my emphasis):
"There is little warning of the approach of the stall except for a slight tail buffeting which may be felt some 5 m.p.h. (kts) before the stall itself. At the stall the nose drops gently. In all cases recovery is straight-forward and easy."
Mid summer in Texas. Dry downburst? Developing dust devil? Either could be forming mid field just as they started take-off roll. A sudden headwind increase as the tail is just about to lift could conceivably have the aircraft prematurely airborne. Then all it would take is a shift in wind direction or intensity to do the rest.
I still hesitate to say 'pilot error'. Looks to me like they did abort as soon as the control difficulty became apparent.
Knowing the (not) recommended short field method for this old bird, it does not look to me like they were attempting anything so risky. Those good ol' boys spend a lot of time and money restoring these lovely machines, so I doubt that they then put them at risk.
I still hesitate to say 'pilot error'. Looks to me like they did abort as soon as the control difficulty became apparent.
Knowing the (not) recommended short field method for this old bird, it does not look to me like they were attempting anything so risky. Those good ol' boys spend a lot of time and money restoring these lovely machines, so I doubt that they then put them at risk.
Some time ago, saw some very serious gyrations very early on takeoff ---- aircraft groundlooped before they got it stopped ---- a rudder hinge had broken.
Tootle pip!!