TAMARAC, FL, USA
N25VV
Classic Aircraft Corp. S-51D
On the morning of the accident the airplane had flown for about 1.2 hours, landed, was refueled, and shut down for a an unknown period of time. After start up the pilot taxied to the active runway, and was delayed in taking off by ATC, due to traffic. The time between engine start and takeoff was about 16 minutes. About 11 nautical miles west of the airport, the pilot radioed the control tower that he was having a problem raising the landing gear and he wanted to return to the airport. The pilot then radioed that he had lost the engine. Radar and radio contact was lost shortly thereafter. A witness heard the engine losing power, and sputtering. The witness also observed the airplane make a controlled descent towards the ground. On-site examination revealed that the approximately 10-foot-high brush, to the west of the ground impact site was bent towards the east, and the area of bent brush was about 20 feet in length. There were no ground scars to indicate that the airplane had any forward movement after impacting the soft ground. A test run of the engine was performed and revealed that when the engine was brought to cruise RPMs, and running for about 10 minutes, the fuel temperature reached 153 degrees F, which set up a vapor lock condition, the fuel pressure needle fluctuated, went to zero, and the engine completely shut down. The engine was allowed to cool and then started again. On the second run the fuel temperature reached 152 degrees F, the RPM and fuel pressure fluctuated, and the engine completely stopped, similar to the first run. A test on a similar airplane revealed that while cycling the landing gear, the wheels would pass in front of the radiator scoop. With the gear partially up, but not in the wheel well, the gear almost completely blocked the radiator scoop, which would have caused cooling air to be blocked or deflected.
HISTORY OF FLIGHT On May 20, 1999, about 1405 eastern daylight time, a Classic Aircraft Corporation S-51D homebuilt airplane, N25VV, registered to Classic Aircraft Corporation, impacted with the terrain during a forced landing near Tamarac, Florida. Visual meteorological conditions prevailed at the time. No flight plan was filed for the 14 CFR Part 91 personal flight. The airplane was destroyed. The airline transport-rated pilot was fatally injured. The flight had departed the Fort Lauderdale Executive Airport, Fort Lauderdale, Florida, at 1351. The purpose of this flight was to accumulate the 40 hours of flight time on the airplane required before certification (at the time of the accident the airframe had a total of 3 hours). Before this flight the pilot had flown the airplane that morning for about 1.2 hours. After landing, the airplane was refueled, and shut down for an unknown period of time. After restarting the engine the pilot taxied the airplane to the active runway, and was delayed in taking off due to traffic. After takeoff, the flight headed west and was about 11 nautical miles west of the airport, when the pilot radioed the control tower that he was having a problem raising the landing gear and he wanted to return to the airport. The airplane was identified on radar as being at an altitude of 1,300 feet, and heading westbound. The pilot radioed that he had lost the engine. Radar and radio contact was lost shortly thereafter. A witness in the area said, "...a small plane flew over head...directly over head I heard his engines begin to sputter, cutting on and off. The plane was travelling...south-southwest...I knew something was wrong. When the engine cut off for the last time the plane started loosing altitude. And turned eastward towards the Sawgrass Expressway. I did not see any smoke or fire while [the] plane was in [the] air...." The witness said by the time he reached the wreckage it was engulfed in flames. The accident occurred during the hours of daylight approximately 26 degrees, 12 minutes north, and 080 degrees, 10 minutes west. PERSONNEL INFORMATION Information on the pilot is contained in this report on page 3, under First Pilot Information. The pilot's personal log book listing his flight hours was not recovered. It was estimated that the pilot had about 3 hours of flight time in this make and model airplane. METEOROLOGICAL INFORMATION Meteorological information is contained in this report on page 3, under Weather Information. MEDICAL AND PATHOLOGICAL INFORMATION An autopsy was performed on the pilot, on May 21, 1999, at the Broward County Medical Examiner's Office, Fort Lauderdale, Florida, by Dr. Lisa Flanagan. According to the autopsy report, "...the decedent died as a result of inhalation of products of combustion and thermal injuries. Blunt chest and head trauma served as a contributing factor." The pilot was found in the wreckage lying on his back. The pilot's seat back support/shoulder harness anchor bar mounts, that held the back of the seat upright, had failed at the mounts. Toxicological tests were conducted at the Federal Aviation Administration, Research Laboratory, Oklahoma City, Oklahoma, and revealed, "No ethanol detected in Vitreous." The following drugs were detected; Triamterene detected urine and blood, Nadolol detected in Urine, 83.3 (ug/ml, ug/g) Salicylate detected in Urine. The toxicology test showed, "...37 percent Carbon Monoxide detected in Blood...0.4 (ug/ml) Cyanide detected in Blood." Salicylate is the active compound that the body makes from aspirin. Triamterene is a diuretic, commonly used (and routinely approved by the FAA) for control of high blood pressure. Nadolol is another medication commonly used (and routinely approved by the FAA) for control of high blood pressure. Both drugs would tend to reduce "G" tolerance, and can result in dizziness when they are first started. COMMUNICATIONS At 1335:50, the pilot of N25VV made initial radio contact with the Fort Lauderdale Executive Air Traffic Control Tower (ATCT), Ground Control (GC) specialist, and requested to taxi to runway 13. The pilot changed frequencies to Fort Lauderdale Executive Air Traffic Control Tower (ATCT), Local Control 1 (LC1), at 1345:05, and said, "...ready to go on thirteen." LC1 answered, "...hold short." At 1348:50, LC1 said to the pilot of N25VV, "...say intentions." The pilot said, "...gonna make a couple circuits of the field then go westbound." At 1349:10, LC1 said, "Unable...traffic is uh circling over the airport with gear problem if you want just depart the area that'd be better. The pilot said, "...okay we'll depart the area northwest bound and you can give us approach control frequency." The flight was instructed "into position and hold," at 1350:20, and was "cleared for takeoff" at 1351:00," about 16 minutes after the pilot made initial radio contact with the ground controller. At 1359:59, the pilot of N25VV transmitted four times, "...executive tower uh mustang 25VV." At 1400:55, the LC1 specialist answered, "...25VV executive tower standby remain clear of delta airspace." At 1402:40, the pilot said, "...(unintelligible) we're gonna have to come back we can't get the gear up." LC1 specialist replied, at 1402:51, "..standby...you at one thousand five hundred." The pilot answered "affirmative at the sawgrass [Sawgrass Expressway]." The LC1 specialist acknowledged the transmission, asked the pilot of N25VV to "ident" his transponder, and gave the pilot his traffic to follow to the airport. At 1403:25, the LC1 specialist said, "...your about eleven miles west one thousand three hundred indicated...fly westbound I'll call your southbound turn about another mile." At 1403:37, the pilot said, "...I don't think I can I'm losing (unintelligible)." The pilot was instructed to "proceed direct to the airport...runway eight." At 1404:05, the pilot said, "...I'm losing the uh I'm losing the engine I don't think I'm gonna make it I'm gonna (unintelligible)...I've lost the engine." This was the last radio and radar contact. WRECKAGE AND IMPACT INFORMATION The airplane impacted in heavy brush, about 50 yards east of a four-lane highway known as the Sawgrass Expressway. The soil in the accident area was soft and sandy. The approximately 10-foot-high brush, to the west of the wreckage was bent towards the east, and the area of bent brush was about 20 feet in length. There were no ground scars to indicate that the airplane had any forward movement after impacting the soft ground. Both wings and the tail section were still attached to the airframe. Both wing fuel tanks were breached. The rear of the right fuel tank ruptured rearward and inboard near the battery. Control continuity to all flight controls were confirmed by either movement of the control or by tracing the control cable. The wing flaps were in the up position. The main landing gear were found in the down position, and both pivot trunnions had come through the top of the wing skin rupturing the fuel tanks. No fuel was found in the tanks. Examination of the cockpit area revealed that the forward cockpit floor, panel, center console, windshield, and windshield frame, had burned from the post crash fire, and were melted. The canopy, canopy frame, and canopy skirts were found melted and completely burned. The canopy jettison system and rails were still in place with the safety pins still in place. The pilot's seat back was found lying back on the floor. The pilot's seat back support/shoulder harness anchor bar mounts were found broken in two. The rear of the fuselage was found burned in half just forward of the empennage. The area of most concentrated fire damage was located in the area of the battery near the electrical relays and switches just behind the seat, near the area where the right fuel tank had ruptured. The batteries were found in their mounts under the floor just behind the wing, and showed extensive heat and fire damage. The master electrical relays and switches were found still mounted to the batteries, and also showed extensive heat and fire damage. The engine was found attached to the airframe, and the propeller was found attached to the propeller flange. The coolant reservoir cap was found off the filler neck, and located on the ground under the engine. The engine felt warm to the touch when it was examined about one and half hours after the accident. The engine was removed from the airframe for further examination. TEST AND RESERCH The engine from N25VV was taken to the facilities of Tom Hahn, Port St. Lucie, Florida, and a test run of the engine was performed on May 27, 1999, under the supervision of the NTSB. The engine was run with all its original parts except for the following changes. One lower oil line fitting had received impact damage and was replaced. The oil coolant recovery can was crushed and replaced. Probes and sensors were replaced with ones that were calibrated to the instrumentation on the test stand. The engine had retained enough oil to run, however, oil and coolant were topped off, and air bled from the cooling system. Before the engine was started, the cooling system was pressurized and checked for leaks. No leaks were found. The fuel system was primed and pressurized with 100 low lead fuel, then tested for leaks. No leaks were found. The oil system was primed, pressurized, and checked for leaks. No leaks were found. The original wiring harness from the accident engine were wired to the test stand. A temperature probe was placed between the fire sleeve and the fuel line between the mechanical fuel pump and the fuel injection servo to digitally read the fuel temperature going into the fuel injection unit. The gear box and propeller were damaged and not used in the test runs. Throttle, propeller, and mixture cables were mounted on the original mounts. All temperature and pressure gauges were calibrated, checked and found correct. The engine started immediately. After a short warm up and stabilization the engine was brought to cruise RPMs. The engine ran for about 10 minutes, with the coolant temperature reading 170 degrees F, the oil temperature 200 degrees F, and the fuel temperature 153 degrees F ( fuel boils at 130 degrees F), setting up a vapor lock condition. The fuel pressure was reading 23 psi, the fuel pressure needle fluctuated and went to zero, the engine then completely shut down. The probe for the fuel temperature was on the outside of the fuel line, and inside the fire shield outer cover, leaving the possibility that the fuel was hotter then what the temperature gauge showed. The engine was allowed to cool and then started again. On the second run the fuel temperature reached 152 degrees F, the rpm and fuel pressure fluctuated, and the engine completely stopped, similar to the first run. The pilot of N25VV had radioed ATC that he was having problems with the airplane's landing gear before his engine stopped. A similar airplane was used to observe gear retraction and extension. The test on the similar airplane revealed that while cycling the landing gear, the wheels would pass in front of the radiator scoop. The pilot stated he was having trouble with the gear staying up and locked. With the gear partially up, but not in the wheel well, the gear almost completely blocked the radiator scoop, which would have caused cooling air to be blocked or deflected. In any case if the gear would not retract completely or was being cycled to go down, the pilot would require power changes while trouble shooting the gear, which in addition to the radiator scoop being blocked would generate more heat and hotter coolant temperatures. (See photo Nos. 10, 11, 12 ) ADDITIONAL INFORMATION The power plant on N25VV was an automotive type 502 cubic inch, Chevrolet V-8 water cooled engine. It had been modified for reliability and reverse rotation. The cooling system had an aluminum radiator in the belly, which cooled the cooling mix. It also had two oil coolers which also used the coolant to cool the oil. N25VV used a dry-sump oil system with a belt driven external oil pump. This oil pump had an aircraft type vain fuel pump piggy-backed on the back of it so that it could be driven by the oil pump shaft. The fuel injection system was manufactured by Airflow Performance Inc., with no fuel return to the fuel tanks, only a pressure relief at the electric boost pumps to maintain 20 to 25 psi of fuel pressure. (Note: The fuel injector manufacture did manufacture the same system with a fuel return to the fuel tanks.) A fuel system with the return to the fuel tank from the fuel servo, allows for a constant flow of cool fuel to the fuel servo. In addition, with the fuel pump on N25VV mounted on the back of the oil pump, the fuel was subject to being heated up by the hot oil in the external oil pump. (See photo No. 13) The airplane was released to Mr. Ronald Schmidt the owner, on May 21, 1999. The engine and propeller were released to Mr. Thomas Schmidt on June 2, 1999.
A complete loss of engine power caused by the malfunctioning landing gear, which blocked the radiator scoop, leading to increased fuel temperature and the subsequent vapor lock condition and fuel blockage. A secondary cause was the pilot's failure to maintain flying speed resulting in the subsequent stall/mush
Source: NTSB Aviation Accident Database
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