TAPE SAGA
Some time ago I arrived at a flying school to carry out an LPC in a Enstrom 280FX. they advised me they had a "bit of trouble" with blade tape, they had removed a piece of tape ( approx 300mm length) off one blade only.. I checked all the other blades and tape, they all looked fine to me, but I would have done all three blades he same. They said they had been flying with it ok.. I commenced the flying, the heli was flying pretty good , with only a small vibration due to rotor/ blade vibration/imbalance, certainly nothing unusual or abnormal for a Enstrom 280.. After 20 minutes carrying out low level exercises in the airfield, we done one circuit - all ok .
During the climb out on the second circuit, at approx 300 feet AGL, a heavy vibration started throughout the aircraft, -obviously from the rotor. At this moment I thought , this is too much for the student, I took control and thinking that I didn't want to continue , perhaps a 4/5 mile circuit, I turned right and right again , with the intention of coming back into the airfield ASAP. Almost immediately the aircraft entered a furious combination of REALLY huge oscillations, shaking and huge vibrations, oscillating in lateral, longitudinal and vertical planes. at this moment , I am not sure if the aircraft was moving around me, or was I going up and down in the seat, . make no mistake , at this moment the aircraft was now totally out of control.!!
It was impossible to to keep the heli in the air for one micro second longer, I entered autorotation, on the way down the vibration was so great I could not speak ( due my body being shook due to massive oscillations), I thought this has to be catastrophic, this is going to break up in flight!!!!! .. The area directly below us was some sort of crop, we had no choice, as I got of lower, it now looked like tall corn. we touched down very smoothly and by some miracle stayed the right way up.. we were now facing East, with a 10 knot tail wind, so we had landed downwind, we had a bit of a run on for 5 meters or so. When we stopped the "corn" was up to the temperature probe on the windscreen!- it was 5 feet tall! it was not corn, it was some sort of rushes.. As the blades were stopping , I could see a very large piece of blade tape hanging off - I would say it was 15/18 inches in length. I cut it off, and cut a similar piece of the other blades. After checking the heli over we started up and continued the flight. the heli was now flying A1 perfect!!.
A few thoughts on this incident,
a) on the way down it really was just a pure miracle that we stayed the right way up, -- I had no, or very,very little control of the aircraft..
b) I really cannot describe the vibrations and oscillations on the way down , other than to imagine , try flying with one blade off!!!
c) I have had blade tape come off countless times before, in many types of heli, most without incident,, but 12 years ago I did have a similar incident to this , again in an Enstrom - 280c, again it WAS out of control, but the forces and oscillations were very slightly less,* on this occasion, I felt the seat belt pulling and tugging at me on the way down , had it been undone I feel I would have been thrown thru the door!!
d) it was just pure luck there was a landing site below ( even if it wasn't the most suitable).
e) had the incident occurred above a non suitable landing site, i.e. town , houses, valley or forest the outcome would have been very nasty.
If you have blade tape fitted, check it, check, - check it again more thoroughly and then check it again!!
Final thought, blade tape, -- it really should be banned !!!!