First, I am relieved everyone made it out and wishing a speedy recovery for those that were injured.
For those that haven’t read it here is an excerpt from the NTSB preliminary report
Quote:
“The co-pilot, who was the flying pilot (FP) reported that prior to the flight, it was briefed that he would perform the takeoff. He stated that the captain taxied the airplane to the runup area, where all pre-takeoff checks were completed; the captain then taxied the airplane onto runway 19. The co-pilot further stated that he then took control of the airplane, provided a pre-takeoff brief, and initiated the takeoff sequence. About 10 seconds into the takeoff roll, the airplane drifted right, at which time he applied left rudder input. This was followed shortly by the captain saying that he had the airplane.
The captain, who was the non-flying pilot (NFP), reported that during the initial stages of the takeoff roll, he didn't recall the airplane swerving to the right, however, recalled telling the co-pilot not to push the tail up because it was heavy; he also remembered the airplane swerving to the left shortly thereafter. The captain stated that he yelled "right rudder" three times before taking control of the airplane. He said that as he put his hands on the control yoke, he noticed that either the tail started to come down or the main wheels were either light or were just coming off the ground as it exited the left side of the runway. The captain said that he knew the airplane was slow as he tried to ease it [the airplane] over [to the runway] and set it back down. Subsequently, he felt the 'shutter of a stall," and the airplane turned to the left and impacted the ground. After the airplane came to a stop, a postimpact fire ensued, during which all the occupants of the airplane egressed through the aft left door.
Examination of the accident site revealed that the airplane came to rest upright on a heading of about 113° magnetic, about 145 ft east of the left side, and 2,638 ft from the approach end of runway 19. The postimpact fire consumed the fuselage from the nose cone aft to about 3 ft forward of the left side cargo door along with a majority of the wing center section. No evidence of any flight control locks was found installed. The tailwheel locking pin was found in place and was sheered into multiple pieces. Vegetation (grass) within about 200 ft of the main wreckage was burnt from the postimpact fire. The wreckage was recovered to a secure location for further examination.”
I by no means know what happened, but as a pilot certified to fly the DC3 I might be able to add a little insight to the discussion on procedures and aerodynamics for large multi engine tailwheel aircraft.
First once the Captain becomes the NFP in the initial stage of the takeoff run he is most likely heads down ensuring the takeoff power is set and engines are operating normally. You cannot just firewall a DC3, you will over-boost it and if power is added to quickly a propeller over speed is a real possibility. So the NFP’s head will be down looking at gauges in the early part of the takeoff run.
It can be difficult to rig the cable linkages so power comes up evenly on both engines simultaneously with throttle advancement. One can lag behind the other and that can cause directional issues early in the takeoff roll. A small slug of water can momentarily cause the engine to hesitate and also induce a momentary asymmetric power condition. IMHO most pilots are trained well enough to abort a takeoff if there are issues with a power plant, however we are less inclined to abort a takeoff for what starts out as a small loss of directional control (we think we can save it)
It was very warm 84F and the Captain stated it was tail heavy. The aircraft is going to be slow to accelerate. In the 3 point configuration at slow speeds the fuselage can block out a good portion of the rudder which makes rudder input ineffective early in the takeoff roll. The tail ideally should be firmly on the ground until some significant airspeed (40 mph) is attained, then raised or up in the air so the fuselage is approximately level. If the transition is slow or the tail Is left in between the three point and the level attitude the rudder effectiveness will be decreased. My first few flights in the DC3, we were empty and the CG was near the FWD limit. The tail nearly raises itself after the application of power and the rudder is fairly effective. After my training and check ride was completed, we had a flight that put us at max gross weight and the CG just forward of the aft limit. It was a totally different feel. The acceleration was slow, it took considerable nose down elevator to raise the tail and the rudder was much less effective.
The lockable tailwheel works well in helping keep the airplane straight. However if directional control is lost and the tail remains on the ground or is put back to the ground the lockable tailwheel will make it more difficult to correct the deviation in the event the takeoff is continued.
The ailerons on the DC3 are are over 48 feet in length with a lot of travel on 95 foot wingspan. The adverse yaw created is huge. The Captain that taught me how to fly the DC3 showed me very early on that with the tail wheel unlocked you could “steer”the airplane on the ground at taxi speed. The setup was calm winds and maybe 5 to 8 knots of taxi speed, a big clear section of taxiway and run up area, tail wheel unlocked with no rudder input to keep the airplane tracking straight. He then instructed me to turn the yoke to the right and the airplane almost immediately started to turn to the left. After that demonstration he told me one of the most important phrases I learned in the DC3 and that was to “steer for the ditch.” The adverse yaw created by the down aileron creates so much drag the airplane will turn on the ground but it will go opposite the direction you turn the yoke. If a pilot has a bad habit of trying to steer the airplane like a car and as the airplane drifts left makes a control input of turning the yoke to to the right , the left yaw will be exacerbated greatly. If right rudder was added at the same time it might not be effective as the aileron input cancels out the rudder correction. A pilot has to be very cognizant of any aileron input made as it will result in forces that change the direction the airplane is headed.
Once again, I am glad all made it out safely.
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