Recall reading the article in "Spotlight" of the 707 spin/crash. The 130 spin and a RAAF P-3 spin were also mentioned. RAAF flight safety should be able to help. Have found them most helpful in the past.
Edited to add I found this at
E Story.doc - Windows Live
THAT EVENTFUL DAY
23 SEPTEMBER 1966
My fourth flight “solo” as a fully qualified Flight Engineer with No 36 Squadron, flying on a Lockheed C-130A “Hercules” aircraft. It was an afternoon training flight and was planned for 2 X 2:00 hour sessions starting with a 1300 Hrs take off.
The crew were: -
Captain Flt Lt Bruce Clarke Q.F.I – I.R.E
Copilot (conversion training) Flt Lt Arch Streeter
Flight Engineer Sgt Barrie Wallis
Loadmaster Sgt Les Wells
The aircraft was: -
RAAF Hercules A97-207
The base was: -
RAAF Richmond, NSW
It was proposed that after the first 2Hr training session the pilots would change over, with engines running and the second session would carry the same S.N.C.O’s. We were planned to take off at 1300 Hrs so the Flt Eng and Loadie preflighted the aircraft and when the pilots arrived we were briefed by Flt Lt B.C. Clarke as to the content of the training mission. He said that we would be going out to the training area to the North West and demonstrate and practice “Stalls”, both clean then dirty.
We were the only aircraft in the training area at that time on that day so, B.C. said we were planned to do these stalls at 5,000 ft AGL over the Blue Mountains, however for this session we would go up to 15,000 ft to save time, and after recovery from the last stall we would carry out a practice medium level ADF approach. All done we “started and departed” and in transit to the training area the Loadie Les Wells secured the cargo compartment of loose articles that could become missiles during the stalls.
Almost to the training area B.C. Clarke called Les and checked the condition of his domain, and when told all was ready, B.C. told Les to come forward and strap into the vacant Navigator seat for the practice stalls. The layout in this session was Arch Streeter (who was on a conversion course) was occupying the left hand normal Captains position and the Co Pilots seat was occupied by Bruce Clarke. When the Flight Deck was also made secure we started our first stall, a simple “clean” stall which was demonstrated and an effective recovery carried out. During the stall Bruce Clarke demonstrated that when in the stall even though the aircraft was normally stable, very little lateral control was available however on the application of power the aircraft would actually climb out of the stall if necessary.
During the next stall Bruce Clarke entered the stall by closing all throttles to the Flight Idle position and raised the nose. When in the stall which was charted to occur at 95Kts, Bruce Clarke demonstrated the absence of lateral control by rolling the ailerons from full left to full right without the aircraft responding and when the speed decreasing past the stall figure Bruce Clarke said that the longer the aircraft is left in the stall the buffet gets worse and all control is lost.
Just past this point the aircraft rolled to the Left and Bruce Clarke attempted to pick up the dropping wing, but with no lateral control the aircraft rolled to onto its back and entered a spin. At this point Bruce Clarke announced that we had rolled into a spin and he had taken standard recovery action. So we went down and during that spin, after what seemed an eternity Bruce said that the aircraft was not responding but standard recovery action held on.
Again after what was a lifetime to us new members, the aircraft responded and the spin stopped, Bruce Clarke said we were out of that but now we have to get it on the ground. I carried out a visual inspection from the cargo compartment but nothing was out of the ordinary much to my surprise. We made a speedy return to Richmond and once on the ground logged the aircraft in for a high “G” inspection. At the bottom of the spin at the pull out which was between 7000 and 8000 ft we pulled 3.2 positive “G”.
Next came the investigation as to why a normally docile and well-mannered C-130A would spin. After all the evidence was put together no defect could be blamed, however the mechanics of the Hercules was partly the cause aggravated by humans. To explain this further one has to come to grips with a constant speed Turbo Prop engine. It always runs at the same speed however, to make it function correctly, by adding more fuel to the engine the system will increase propeller pitch rather than increase RPM which is governed and so cause more work to be done, consequently when the fuel flow is reduced to the Flight Idle position the propeller pitch will decrease towards the zero position and stay there. Now with four engines the Flight Idle position in relation to the blade angle was not the same, so that at Flight Idle there were four different power settings.
Next at the Flight Idle position if the fuel is low, this can cause the propeller pitch to decrease below zero degrees and become negative. Obviously this is not a desirable thing to happen so when the “Negative Torque” reaches a set figure the mechanical (NTS) system will physically attempt to increase pitch and thus hold it at a predetermined value, this being -1400 Inch Pounds of Torque.
So now to put this knowledge into our docile C-130A. In the air when starting to practice the stalls, the four throttles were pulled back to Flight Idle and in this case engines 3 and 4 on the right hand side they remained in positive thrust, just how much I cannot remember, then engines 1 and 2 on the left hand side were producing Negative thrust just above the N.T.S. system activation. Now in the air as the speed decreased the stall started and as it was held there we lost aileron control, then a short time later engines 3 and 4 which were producing positive thrust attempted to accelerate that wing, thus producing lift, while engines 1 and 2 were in Negative thrust and attempting to decelerate that wing, thus creating drag. It naturally followed that without aileron control and differential thrust there was only one situation that would occur, and it did.
One outcome was to then make a Standard Operating Procedure requiring that BEFORE entering stalls when the power was reduced to Flight Idle a power asymmetry check was carried out and all engine outputs were aligned.
The aircraft involved in this incident was A97-207 and at the end of the inspection it was found that several rivets on the upper surface of the left Hand horizontal stabilizer had popped and there was speculation that these had popped some time prior to the stalls, nothing else. The aircraft was given a clean bill of health and from that moment onwards it never would fly straight again without cross trimming. I never flew in 207 for another six months but do remember its flying characteristics.
By Sgt Barrie Wallis, Flight Engineer