ANC93LA153

The pilot stated that just after takeoff, he encountered a strong gust of wind that caused him to lose control of the airplane. He said the left wing suddenly went down to almost 90 degrees and hit the ground. The airplane then cartwheeled and came to a stop. The pilot, passenger, and three ground witnesses said the winds had been variable and gusty. The pilot waited on the runway for several minutes for more favorable winds before starting the takeoff.

History of flight

On August 18, 1993, at 1230 Alaska daylight time, a wheel equipped Piper PA-18 airplane, N54938, operated by Tamarack Air, Ltd. of College, Alaska, crashed during the takeoff climb from a remote sheet hunting strip on the Little Delta River, located approximately 47 miles southwest of Delta Junction, Alaska. The airline transport pilot sustained minor injuries, the passenger was uninjured, and the airplane was substantially damaged. Theunscheduled local domestic passenger flight was operating under 14 CFR Part 135 at the time of the accident. Visual meteorological conditions existed, and a Company VFR flight plan was filed.

The pilot and passenger stated that just after taking off, they encountered a sudden strong gust of wind. The left wind went down almost 90 degrees and hit the ground. Shortly thereafter, the plane's fuselage collided with the ground. The plane turned 180 degrees from its initial heading before coming to a stop. Both also said the winds had been calm on the ground, but gusty in the air. The area is surrounded by mountains within one mile that rise to heights over 7,000 feet above sea level. The pilot said he had built the 550 foot long strip in 1965, and estimated that he had made from 500 to 800 takeoffs and landings there since that time. He said there was a wind indicator (flagging on a pole) at both ends of the strip.

Additional information

According to the National Weather Service, at 1153, the weather at Delta Junction was 20,000 thin scattered, 50 miles visibility, 61 degrees Fahrenheit, dewpoint 36 degrees Fahrenheit, winds from 200 degrees at 29, gusting to 42 knots, altimeter 29.79 inches of mercury. Higher winds were recorded at 42, gusting to 51 knots.

The accident was witnessed by three persons at the departure strip (Tom Johnson, Terry Fike, and Terry Johnson, all of Anchorage, Alaska.) They reported that the pilot had waited on the strip for several minutes for the gusty variable winds to become more favorable before he started the takeoff roll.

On August 25, 1993, the pilot, William J. Lentsch, telephoned the NTSB Investigator-in-Charge (IIC) concerning the accident. He said he thought he lost control of the airplane and crashed because one of the wing fuel tanks had broken loose from its mounting straps and came out of the wing during flight.

The fuel tank retaining straps and clamps were examined by Alan Stockridge, an aircraft mechanic from Fairbanks, Alaska. He stated that the wing was damaged extensively during the crash, and it was his opinion that the fuel tank broke loose at that time.

On September 20, 1993, the NTSB IIC received the pilot's eight page statement of his account of the accident. In the statement, he explains how he thought the accident was caused by a split flap condition (one flap retracted while the other flap remained extended). He stated that he had jammed a large backpack frame into the airplane and thought it had pinched the flap cable on one side; thereby possibly restricting its movement when the flap handle was moved to the up position.

Following this report from the pilot, FAA Airworthiness Safety Inspector Clifford H. Smart examined the flap cables and airframe. He stated that he found no evidence to show that the flap cables had been pinched, and in his opinion that was not what caused the pilot to loose control of the airplane.

An official of Tamarack Air reported that the results were negative from the pilot's post accident toxicological tests.