N4285V

On November 28, 1993, about 1230 EST, a Challenger II, experimental homebuilt airplane, N4285V, was substantially damaged during an uncontrolled descent following takeoff. The commercially certified pilot with flight instructor rating received minor injuries. The flight was a local flight with no flight plan on file. Visual meteorological conditions prevailed with reported winds of 8 knots.

The pilot stated the aircraft began a 90 degree turn to the left after takeoff and would not respond to right bank correction. The pilot made a series of left climbing turns in order to climb over hangers and reported stability could only be maintained in left bank attitudes.

After reaching a safe altitude the pilot checked control responses and states "movement appeared normal but right bank still could not be made. Flaperons were positioned near neutral".

The pilot attempted a series of left circles to approach runway 27 for a landing. He states "instead of landing straight ahead on grass as intended, the left bank continued. Either the left wing touched weed growth or stalled, or both. The aircraft did a (3/4) turn spin to the left and impacted ground on right side of nose and right wing".

The pilot states this was the first flight since the installation of doors with a modification kit. He states "I think from response to normal control input that the doors changed airflow to the pusher prop and empennage. That the fixed left rudder trim and torque effects of prop might have contributed highly to problems described. From the back side, the pusher prop spins left. A modification kit increasing size of fin area is available. Extending the fuselage length and leverage, or enlarging fin, or both might provide necessary control. Challenger newsletters indicating same problem, to some degree or other, are attached".

Challenger Newsletters from the International Challenger Owners Association are attached to this factual report. In five newsletters from the December, January, February 1991 newsletter to the September, October, November, 1993 newsletter, there are owner statements which all state basically the same that "The airplane flies great with the doors off and has been a lot of fun. However doors on is another story. The two place Challenger with the doors on requires a lot of rudder and is somewhat unstable".

In the March, April, May 1993 Challenger newsletter there was mention of a modification from the UK stating "The main difference as you will probably be able to see from the photo is the UK spec has a larger fin and rudder, since the opinion of everyone who flew it in the early stages over here, was that there simply was not enough rudder available. A factory mod was produced, resulting in another 25% on the dorsal main fin and rudder, which has drastically improved the handling of the aircraft, particularly in turns and close to the ground at lower speeds. Why all Challengers don't have this, I just can't figure out".

This investigator talked to the President of Quad City Ultralight Aircraft Corporation. He stated with doors on the pilot does have to stay ahead of the aircraft. This was confirmed by a letter from the EAA (attached) regarding their research which states "Dave says that the aircraft is rudder sensitive and with doors on in normal flight you can't take your feet off like you can in some airplanes. The airplane is specifically designed this way, as the customers seem to prefer it that way. If I understand correctly, Dave says that it yawed to one direction and the pilot tried to correct with the aileron, which will not work on the Challenger I and II. Once you get the hang of using the rudder properly, flying it is a piece-of-cake. If the pilot had taken some dual, Dave feels that he would have had no problem. He also says that most ultralight aircraft or light planes, like this one, are rudder dominant. He also is aware that the English had a problem with the aircraft and that their regulations are much more strict than ours. They have a bigger dorsal fin and rudder, as their pilots were not used to the light rudder, as it is not self-centering. Dave further states that the pilot had the opportunity of flying with any one of three dealers in Michigan and could have had a proper checkout before flying. Dave has produced over 1,300 airplanes in 11 years and their accident record is good, which I must confess is correct from the information that we have".