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ACCIDENTS AND INCIDENTS
"I am sorry to have to report an
off airport landing with my Long-EZ due to loss of power on take off. The result was
damage to the landing gear, canard and left wing.
The Long-EZ, serial no. 132, is powered with a Continental 0-200 and has been a joy to fly for the past two years and 200 hours flight time. Recently, I flew the Long-EZ to a nearby airport in Alabama for an "Aviation Day" event. About an hour after landing, I was to participate in a flyby. It was about 12 minutes after I started the engine, with outside temperatures near 90 degrees, before getting into takeoff position. The oil temperature was up to 200 degrees and I was considering canceling the flight when we were cleared to go. Even though the engine was very warm, the temps were in the green and a crowd was watching, so I decided to takeoff. The takeoff run was normal although an observer later told me that he saw what appeared to be smoke coming from the engine. The climb seemed a little sluggish and, at approximately 60 feet, the engine lost power.
I verified that the booster pump was on and, pumping the throttle, got a couple of very brief surges of power. The flight was so short and I was so busy looking for a place to land that I did not look at the fuel pressure and did not attempt to switch fuel tanks. The aircraft was put down in virtually the only field available. It was about 1000 feet long with the always present power line on the approach end and was ringed with trees. Touch down was 1800 feet beyond the end of the 4300 foot runway and was 300 feet into the field beyond the power line. The aircraft slid 240 feet in a straight line. It remained upright with the engine still running at a rough idle. The ELT was activated. The engine was shut off with the mixture control. I was not bruised or scratched.
The aircraft touched down nose low because the canard was stalled and apparently the left wing was slightly low. The nose gear shock strut broke and the lower NG-15A casting cracked and came off the gear strut. The gear strut appears to be undamaged. The left main gear leg twisted with some damage to the gear attach point. The prop did not make contact. The left tip of the canard touched, breaking the canard with some damage to the P-22 bulkhead. The left wing made contact with slight damage to the lower winglet and buckling the skin aft of the outboard attach fitting.
I fully expected to go through the trees at the end of the field and was surprised that the aircraft stopped just beyond mid field. If the plane had not been stalled in, it would have touched down much further down field and would surely have gone into the trees with probable injuries to me and major damage to the aircraft. I feel very fortunate to have avoided injury and to be left with a repairable aircraft. I am impressed that the Long-EZ could be put down in so small a field with so little damage.
I have not been able to identify a probable cause for the power loss. The engine was restarted about an hour after the landing. It ran and accelerated smoothly and both mags checked ok. There was an unusual sooty deposit in both exhaust pipes. After the aircraft was brought home, the engine was run and checked again. The throttle, mixture and carb heat controls have been checked. The fuel tank vents (two per tank) are clear. The fuel flow rate with booster pump on is 25.8 gal./hr. for both tanks. The booster pump was replaced in Nov. 1988 as recommended by newsletter CP 57, pg 7. The engine driven fuel pump has a cooling shroud as per CP 48, pg 4.
It seems likely that there was a partial vapor lock due to the heat soak from the warm engine and minimal cooling air flow. It is also possible that the engine driven pump over heated and caused a loss of pressure. When I look at the carburetor mounted behind, and very close to, the oil tank on the Continental, I suspect the possibility of fuel boiling in the carburetor. This however will not be easy to prove since I don't plan to try another takeoff with an overly warm engine."
William R. Perry
Editors comment: We have talked at length with Bill
Perry about what may have caused his loss of power and we suggested carb ice as a
possibility. Certainly, as a student pilot flying a C-150 (Cont. 0-200) in the humidity of
the midwest, we saw carb ice on take-off at least once when it required full application
of carb heat just to make it back to the runway. This would also explain why the engine
ran fine an hour later - the ice melted. Whatever it may have been, we have asked Bill to
keep us apprised of anything he may come up with during his rebuild and, of course, we
will pass it on via the CP.
PROP BOLT TOROUE. (Letter from John Bridges to Arnie Ash passed on to RAF)
"How many times have we been
cautioned about checking the torque on wooden props, especially when climates change?
Here's the new wrinkle that happened to me.
My Long-EZ, N642JB, has been flying since July, 1987, and has accumulated 283 hours. have made several trips from Michigan to Phoenix, been to Sun-&-Fun twice, and many more short hops like Rough River and Oshkosh. It has been a great joy to fly and share with others. While in Phoenix, about a year ago, I talked to Great American about the poor climb performance with my 62x62 prop and 0-235CI engine. They recommended a change to a 60" pitch would solve the problem. I flew to San Luis Obispo on the next day and Fred Griffith met me at the airport where we installed the new prop. I must add that Fred is a super guy and really helped to solve my problem.
The new prop did the job - better climb performance and I could see 2800 RPM at full throttle.
Returning to Phoenix, I removed the spinner and re-torqued the bolts. After returning to Michigan, I checked torque again at 10, 25 and every 50 hours.
Last November, I flew the airplane back to Phoenix for the winter. The airplane stayed in Phoenix until I headed for Sun-&-Fun on April 6th. I checked the prop torque on April 5th to make sure the dry climate wouldn't come back to haunt me. Prop torque was perfect and had remained unchanged all winter.
I arrived at Sun-&-Fun on April 6th and stayed until April 13th, and then flew home to Michigan. During the next week, I changed oil, cleaned the airplane and checked prop torque - no change.
On April 23rd, I flew over to visit a friend at another airport. Upon departing that airport, I could not fully retract the nosewheel. It was rotated 90 degrees from normal. I tried twice to coax it back into position without success. Since I only had 20 miles to go, I decided to leave it partially retracted. This was the first time this had happened. About 10 miles later (about 1000 AGL), I started to make a climbing turn to the left and reduced RPM to 2000, and all hell broke loose. I thought I had been hit by another airplane.
These were my thoughts as the airplane began shaking violently. I looked out - both wings still on - something's wrong with the engine shut everything off - slow so vibration stops look for a place to land. The City of Rochester was in front of me so I did a 180 degree looking for a place with no houses, people, cars, wires or trees. There it is, green grass - looks flat - plenty of open field - set up for landing - gear down - slow it down - trees at the other end of field set it down. Snap, the nosewheel assembly departed the strut - canopy shattered - nosewheel collapsed, mains folded - wheel pants (Sport Flight) stuck into wings - now I was totally a sled - started turning to the right - left tip of the canard dug in, cut into the fuselage and broke - left wing tip dug in - wing broke at comer of wing spar to inboard aileron cutout - went a few more feet and stopped.
FAA came out to investigate and stated I had picked the best place around but, if I had kept it up another 30 feet I would have missed the tire ruts that I couldn't see, and probably saved the aircraft. What caused the sudden vibration? One prop blade broke off at the hub. Why? The threads on the prop bolts had bottomed out. Why? Apparently, the prop hub was a little thinner.
The prop dried out during the Phoenix winter and the bolts could have been about 1/8' shorter. I was reading torques, but there was no clamping pressure on the prop. I also feel the nosewheel hit something on take-off and threw it into the prop, causing damage to the blade and when I retarded the throttle, it was all over.
Let this be a lesson to all of us, not only to check prop torque, but to also recheck bolt length to ensure any slight variation in hub thickness will not result in running out of threads.
PS I suffered a minor cut on the forehead (no stitches) and a very sore shoulder - it cracked the left side of the fuselage."
John E. Bridges.
Editor's comment. Many of you will recall a similar
incident that happened to Dick Rutan while flying the prototype Long-EZ, N79RA, (See CP
32, page 5). Due to the spinner backplate interfering with a radius on the prop extension,
the prop bolts did = provide any squeeze up or crush between the crush plate and the prop
extension. Neither the drive lugs nor the prop bolts have anything to do with driving a
wood prop. @l the friction between the flange on the prop extension and the forward face
of the prop, l@ the friction between the crush plate and the aft face of the prop, drives
the prop. Once you lose the friction grip on the prop by bottoming the bolt threads, as
John did, the prop is free to oscillate slightly with each piston firing stroke. This
begins to elongate the drive lug holes in the prop and causes vibration. If the pilot
allows this to continue for more than 30 seconds or so, the bolts will break at the base
of the threads and the prop will depart the airplane (which is what happened to Dick!).
The damage to the prop is usually quite graphic, huge elongation of the drive lug holes
which causes the bolts to bend back and forth and ultimately break, but also usually the
prop face will have evidence of charring. Yes, lots of heat is generated by the
oscillation and it burns the wood! We believe John's problem was bolts bottomed on the
threads. Therefore, little or no gripping pressure between the crushplate and the
extension flange, therefore prop oscillates, elongates drive lug holes, perhaps chars the
wood, vibration sets in and John shuts the engine down. Prop stopped near vertical and
when the gear folded the lower blade broke off when it struck the ground. The loss of one
prop blade almost certainly did not occur in flight. We would be most interested to
examine John's prop, but the above is our opinion here at RAF based on many accident
investigations as well as some personal experiences.
A FLORIDA VariEze crashed during an
attempted forced landing and the pilot, the only occupant of the aircraft was fatally
injured. An eye witness reported that the engine cut out and that the pilot subsequently
attempted to land on a road. A local EZ builder/flyer reported to RAF that he believed the
pilot may have accidentally turned the mag switches off. The mag switches in this airplane
were small toggle-type switches mounted high in the center of the instrument panel close
to the air vent. The theory is that perhaps because it was hot, the pilot may have
attempted to adjust the air vent and accidentally knocked the toggle mag switches off. Of
course, no one will ever know for certain, but this theory is plausible and we have
certainly seen mag switches mounted like this that could easily be inadvertently switched
Use only the "locking" type switches, the ones you have to pull out to move up or down. Or place the switches where they could not possibly be accidentally turned off or on without the pilot's knowing about it.
A TEXAS LONG-EZ experienced an
unintentional landing on the dirt foundation of a future runway, causing some minor damage
to the airplane but no injuries. During a fly-in, while flying in a high speed/low speed
competition, this pilot was slowing to his minimum flying speed and was indicating 65
knots, very nose high, when he noticed he was sinking. At what he judged to be about 20
feet, the nose pitched down. He immediately applied power which he said had no effect, so
he pulled the power to idle and held the stick full back. The nose continued dropping and
he hit the soft dirt in a 3 point attitude. The Long-EZ slid to a stop in about 300 feet.
Damage was minor and he had it flying again the next day.
The weather conditions were good, no rain, light winds and the airplane was being flown very light. What caused this problem? We experienced a situation very similar to this once ourselves, but at the time we were flying with an experimental canard airfoil and it was raining. This test airfoil was retired and not put into production!!
It is not normal for an EZ to behave in this way. There have been rumors over the years that EZ's were prone to this behavior, but that is simply not true. At least of a plans built, correctly rigged EZ. A Long-EZ using the original GU canard, with the elevator rigged so that the full aft stick (FAS) mechanical stop is at a point beyond maximum lift coefficient, approx. 22 degrees trailing edge down, would possibly exhibit the same characteristics described by this Texas Long-EZ pilot.
It is critically important that the maximum attainable lift on the canard occur at full aft stick, A perfectly built canard/elevator will reach maximum lift at 22 degrees of elevator deflection, however beyond 22 degrees, the lift available will decrease. When you do your initial flight testing check that you are, indeed, getting maximum lift at full aft stick.
We believe it is possible that the above incident may have been caused, at least in part, by the elevator having been deflected beyond the point at which it allows the canard to generate maximum lift. Another contributing factor may have been an incorrect airspeed indication. At 65 KIAS, a light weight Long-EZ certainly should not be at such a nose high condition that the pilot cannot see forward, nor should it stall at 65 KIAS. This pilot may have been much slower than he thought, and had actually reach the stall condition - normally a pitch bucking as the canard stalls and unstalls. If this were the case, this condition might have been aggravated by the main wing getting into ground effect which would cause a small nose down pitching moment due to the long moment arm of the swept main wing and the "cushion" between the wing tips and the ground.
It must be pointed out, however, that it would be a problem to land an EZ if this were a normal characteristic of all EZ's! After all, we have all probably landed at 65 KIAS or slower many times without having the nose pitch down prior to touch down or even after touchdown. When the prototype Long-EZ was in flight test back in 1979, we landed it many times at full aft stick. This is not a good method of landing but it can be done with some practice. It does not produce the shortest landing distance, however, and is not recommended. It is only brought up here to make the point that a Long-EZ should not do what this Texas Long-EZ did.
As always, we publish reports on accidents and incidents like these above purely in the hope that by reading them, other pilots will perhaps avoid getting into similar situations. If only one pilot is saved from an accident because of RAF publishing these reports, it is well worth it.