One of a helicopter pilot’s biggest worries is losing a tail rotor. It’s happened to me twice and I wasn’t injured either time. So with a bit of luck and skill, it can be coped with.
Twin Squirrel
The first occasion was back in August 1997. I was sitting in the left hand seat of a Twin Squirrel, while a very good friend of mine, Paul Moran, was flying. I actually asked him that day, “Paul, I sometimes get asked if I’ve ever had an accident and I say no. You’ve had a mid-air collision, what do you say?” He replied “I always say I’m the safest pilot to fly with, as the chances of another mid air are millions to one.”
Hours later, at 2000 feet near Leeds, a Katana light aircraft chopped off our tail, vertical fin and tail rotor complete.
The spin was quite exciting! So sudden that my port sliding door detached, never to be found. The wind took my maps, sunglasses, even my headset. My first instinct was to grab the controls, but I could feel Paul flying so I let go again. He had lowered the lever so I grabbed the throttles, looked at him, then pulled them both back all the way.
We were in a pretty steep nose down attitude, but at least it was all corn fields below. I didn’t know if he had cyclic control. I just locked my seat harness and waited. When Paul started a flare, I knew that unless the blades came into the cabin, or we caught fire, we should have a good chance.
With no fin or rotor we were yawed 60 degrees to the right. Paul flared back and to the side. I knew we would roll, so I grabbed the door handle and covered my head. With collective to cushion we touched down softly, but immediately rolled onto our left, then spun 180 degrees as the blades thrashed themselves to destruction.
I was later told radar tracked us as 30 seconds from impact to ground.
I had mentally determined to exit my door, but now next to me was a wall of flattened corn. Paul was above and I thought, ‘If I don’t move quick, he’s going to fall on me!’ I unclipped, got into the rear, climbed the seat backs and threw his pilot’s door up and open, climbing out onto the side.
Paul unclipped in turn and the only injury between us was bruising to his leg as he fell down. I gave him a hand up, then we both jumped down and ran away laughing and exhilarated.
When all we could hear was the ticking of the cooling metal, I climbed back in and threw out our Nav Bags and kit. I phoned the emergency services whilst kneeling on my map to stop it blowing away. Local farm hands ran up so I asked them the address so we could be pinpointed. A newspaper later reported that ‘the pilot was in shock, down on all fours, unaware of where he was…’
An RAF Sea King took us to hospital for checks, but the Katana pilot declined to fly again that day. He had landed in a field nearby, with broken propeller, smashed canopy and a cut to his hand. I never met him, but he was an ex WWII pilot, so I really have been brought down by the Luftwaffe!
Agusta 109
Forward now nine years to October 2006. I’m off in one of our six Agusta 109’s, on a short five minute flight from Redhill Aerodrome to Biggin Hill Airfield. This was to take two regular clients from their private jet to London heliport.
Just after levelling of at 1400 feet, I heard a bang and despite full left pedal, the aircraft rolled into a right hand turn.
I put out a Mayday call and varied the collective power to see if I could affect the yaw, which would indicate a jammed rotor, but no luck. I knew I had lost any tail rotor effectiveness and would have to make an engine off landing. At least I was flying and maintaining height.
Redhill Aerodrome came round into view, but as it’s a grass field, I decided to continue the right turn and make my landing on one of the hard runways at Biggin. This was to help with an expected fast run-on and to reduce the chance of wheels sinking in and a rollover.
Cross-controlling with the cyclic to the left I managed to fly a mile or so toward Biggin Hill toward my planned descent, but suddenly, with a horrible wrench, the machine pitched up and spun.
I thought the aircraft was coming apart. I instantly lowered the collective, pulled both throttles back to their idle stops and selected gear down, in three quick, instinctive motions. I made another Mayday.
A witness on the ground reported seeing the machine spin ‘as if the blades had stopped and the body had turned’. Biggin Hill is at 600 feet above sea level, so the ground below me was only 900 feet or less away, steeply sloping in places and covered in small irregular woods.
I came out of the spin pointing to a paddock. I knew I was downwind, but this was going to be the place anyway. My eyes went from field to rotor RPM and back to field. I had no time to check ‘Three Greens’; the wheels were either down or they weren’t. I had no time to shut off the engines. I knew speed was important to keep straight, but I didn’t look at the air speed indicator. I just kept the nose down with the ground passing under me, as I flew toward the field.
I didn’t flare much, as I wanted speed to keep straight. I raised the nose enough to get the main gear onto the ground first, using the collective as little as possible. As we rolled across the lumpy grass at about 60 knots I lowered the collective slowly to avoid yawing and a rollover. We slewed to the right and came to a halt.
I shut down the engines, tried unsuccessfully to radio any station, then got out. First I saw a missing tail rotor and gearbox, then a shredded lower fin. After telephoning Police and Air Traffic I noticed the port engine exhaust pipe was missing. I lifted the engine cover and a fractured clamp dropped to the deck. This had allowed the exhaust pipe to detach, which hit a main rotor, before smashing the tail rotor, causing the tail-rotor and gearbox to depart.
The next thing I noticed was the upper vertical fin was leant over at about 30 degrees. I could wave it from side to side. The second event, when the helicopter spun, is thought to have been caused by failure to the stiffness of the upper fin, the structure being much weakened when the gearbox ripped out.
I walked away for a second time without a scratch. I hope I won’t need such luck and skill again.
Conclusion
The exhaust clamp was unlifed with no call for inspection. It is now required to be inspected each year.
A Fenestron or Notar would have helped prevent the second accident, but not the first.
Flying to a clear area for an engine off using the fin is a good idea, so long as the fin holds up.
Getting the lever down quick is paramount, not something all twin helicopter pilots practice much.
Forward G of G with loss of weight at the back seemed within cyclic control range.
Speed is key to keeping straight.
Twin pilots don’t practice engine-off, run on landings. I guess (depending on flight experience) you retain enough skill from flying single engine helicopters in the past.
Philip Amadeus is Chief Pilot and owner of RotorMotion.
This article Copyright Helicopter Life 2008