I suppose I must be a magnet for T/R happenings. No 1 ... as a 100 hour pilot in 1973, I experienced a T/R shaft break between hangar bearings number three & four at circa 100 feet on lift-off from Shoreham when the two loose ends hammered into the top tailcone of a 280, non turbo version. Having no idea what to do, I simply dumped the lever in panic and as the heli was about to hit the ground I raised the collective. Accidentally I had at least unknowingly used the basics of a proper response. The aircraft stayed upright.
Number two was again at Shoreham in an air test hover of a 28A when I remarked to the engineer, one Tony Ticehurst that the MAP was at continuous maximum, quickly followed by a loud bang as with the extra power going through ... the transmission seized. A kindly engineer had actually re-fitted the T/R blades trailing edge first! (Yes you can do it and being a clever newby .. I didn't spot it) We touched down safely in a LEFT turn!!! As I later considered the sequence, there was no way the airframe could have rotated left, so I quietly went down to the apron to inspect the skid marks which showed an arc in the tarmac to the left. It took some time before I realised that in my state of arousal, (no puns please) I had slammed the throttle closed the instant the failure occurred effectively producing an engine failure before the blades had slowed.
Number three was at the WHC event at Cranfield in 1986 when pulling a full power torque turn the left hand blade of a 280C intercepted the control cable which allowed the loose end to wrap itself around the transmission whereupon I experienced a second T/R transmission seize. Having significantly thought through the failure now I managed to keep the speed at 75 knots and power below 18 MAP and complete a run-on landing circa 65 knots. The skid marks were around 200 yards.
Number four failure was during a display sequence for Noel Edmonds 'Crinkley Bottom' event when the above failure was repeated. I produced a second speed run-on landing on the local cricket pitch. Now I was worried.
The Enstrom factory got interested as they had experienced a similar failure on a crop spraying task in USA. On the Enstrom system the problem is caused by the rubber bush flapping stops become oiled and soft and this combined with a slack T/R control cable was allowing the blades to flap excessively and slice through the cable at the output position. (The engineer sent my 10 year old son down the tailcone to install a new cable.)
That was in 1991. Now armed with the info and with the factory repositioning the output hole more inb oard and further from the blades, (known now as the Kenyon hole!) Subsequently and before carrying out a display sequence, I ensured that new T/R stops were fitted where required AND the control cable turnbuckles were tightened to the max MM figure.
Now forward to 1999 when the UK distributor asked me to display their latest 280 FX at the Biggin Hill event. A daft case of mis-communication if there ever was one as I shouted across the hangar floor to the duty Saturday morning engineer ... "have you done the tail rotor?" "Yes," came the reply. Sadly for me he only meant he had checked the cables as per the standard MM figures and during my display I promptly lost the tail rotor for a fifth occasion. By now I had a good idea how to cope with the problem and after three dummy passes I again managed to put the helicopter down on the right skid with a right cross wind at high speed luckily remaining upright in the landing roll. God bless the CAA but I did get that year's 'Flying Safety Award' for my effort. Apparently a spectator was later asked what he thought of my display ... "Very good at first" ... "but it got a bit boring at the end as the pilot went round and round the circuit!"
Safe flying to all out there.
Dennis K
I have written up my full recommended sequence of control handling for such an event. For interested parties, just E-mail LOOP (
LOOP.aero) and they will post you a back copy for a couple of Bob.
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