20010705022339A

(-23) On July 5th 2001, inspector dunlop was requested to go with Mr. Rolandos lazaris and Mr. Bruce mcgray to investigage an airplane accident in the vicinity of Potomac airfield, MD. (Kvkx). We were given directions while en-route by the attending fire chief via a cell-phone. We arrived at the scene at approx 13:00, EST and were met by a corporal pearce of the Maryland state police. Corporal pearces' barracks telephone number is 301-568-8101 the office i/c the investigation is sgt. walker. The troop commander is lt. shroker. Cpl. Pearce took us approx. 1/2 mile into a wood and across tinker creek to the site. On the way I asked the trooper if there had been any fire and his reply that there was no fire and infact he had not smelled any fuel fumes at the site. The airplane was totally destroyed and was all in one spot where it landed. The airplane had hit a large tree, that was rotten at the base, and this tree had rotated the airplane around so that it was pointing approx. 180 deg from its original heading. There was very little damage to surrounding trees as the airplane had come down horizontally in a slight right wing low attitude. The left wing being impaled by the tree that came down with the airplane. It had impacted flat on a gravel creek bed. The two occupants, an alan l. williams and his son joey williams had extracted themselves from the wreck and had been transported to prince george's trauma unit by Maryland state police helicopter, trooper 2. I was told that the injuries were mainly cuts and bruises with the son having a broken nose. The tree had cushioned the fall but the airplane had impacted, hard, slightly on its right side with the wings and wing struts failing due to a downwards load. The landing gear was torn off and all parts of the airplane had sustained some damage. The cockpit area was basically complete although some of the roof had deformed downwards. The doors were jammed by wreckage and could not be opened more than approx 2 inc. the instrument panel was deformed by impact from the occupants. The control wheels were in the hard right position. The occupants had released themselves from the wreck without assistance. The fuel tanks were both compromised in the accident but there was no smell of fuel at the scene. The fuel selector and the fuel gauge switch were selected to the right tank. I was able to remove the right filler cap and could not smell any fuel at all. I could not remove the left filler cap due to impact damage. The propeller had mud, and a bend, on one tip where it had hit the soft ground but had not been rotating at the time of impact. The lack of fuel theory was checked and the airplane had picked up 7.9 gals immediately before the final take-off, and a credit card receipt was found for this amount. This would be normal when filling a tank as at any other time you would put fuel into the airplane to nearest gallon. The pilot, mr williams was adamant that he had filled the tank. The rescue party and the investigating officer, sgt walker, had smelled fuel on the clothing of the victims. The pilot's wife had also spent a long time trying to wash and bleach the smell out of shoes and clothing. The lack of a fuel smell at the site can be put down to a very hot day with evaporation and the fact that the airplane had impacted on a gravel creek bed and the residual fuel had drained through the gravel. The theory of contaminated fuel was explored and several airplanes had refueled at the same time as the subject Stinson, with no complaints. The fuel farm is also fitted with a contamination alarm system. The ELT, ebc 102A, had not gone off due to the vertical descent. It was in the baggage compartment, which we could not access due to wreckage blocking the door. We took notes and photographs of the scene and returned to the office. Before leaving I called my supervisor, ed roberts, and asked if the NTSB was going to attend and was told that they were not. The cell phone was very difficult to use at the scene due to terrain. Inspectors dunlop and lazaris inspected the wreckage in hanger 10 at hyde field (W32) on July 9th and 19th. On July 19th jo andrews of NTSB was present. In these inspections it was noticed that the ignition leads for the right magneto were damaged. These leads had been changed, and noted in the engine log, by the pilot, who is not a certified mechanic. The pilot claimed that he had a bad "mag drop" on the three times that he tried to take off and aborted. There is a possibility that these leads had been damaged in the recovery of the airplane but the left side leads were ok. There were also three loose plug leads but they would not have contributed to the "mag drop" or the accident. The carburetor throat was inspected and the venturi found to be intact. The exhaust mufflers were inspected and although the baffles were complete and satisfactory in the left side, the right side baffles were completely disintegrated. There were remains of some of the parts still in the exhaust. It is the opinion of the inspectors that the engine had "mag drops" due to the damaged ignition leads but that the accident was caused following engine failure caused by the right hand muffler disintegrating and blocking the exhaust outlet. It should be noted that the airplane had only flown 28HRS since the last annual inspection and the log books did not show any AD compliance statement or listing. This matter is being investigated further.