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On June 25, 2001, about 1918 Alaska daylight time, a float-equipped Piper PA-18-150 airplane, N7050, sustained substantial damage when it collided with tundra-covered terrain about 80 miles north of King Salmon, Alaska. The airplane was being operated as a visual flight rules (VFR) cross-country government flight under Title 14, CFR Part 91, when the accident occurred. The airplane was operated by the State of Alaska, Fish and Wildlife Service. The sole occupant, an Alaska State Trooper who held a commercial pilot certificate, but limited to private privileges for single engine sea operations, was fatally injured. Visual meteorological conditions prevailed in the area of the accident, and VFR flight following procedures were in effect.
During a telephone conversation with the National Transportation Safety Board investigator-in-charge on June 25, the supervisor for the State of Alaska's aircraft section reported that the accident airplane was one of two airplanes en route to Iliamna, Alaska, after a brief stop at a remote lake. He added that both airplanes departed the remote lake, and no radio communication was received from the accident airplane after departure. When the accident airplane failed to arrive in Iliamna, the pilot of the first airplane refueled his airplane, and initiated an aerial search along the accident airplane's anticipated route of flight. The airplane wreckage was discovered about a quarter mile southeast of the departure lake.
During an interview with the National Transportation Safety Board investigator-in-charge on July 5, the pilot of the first airplane, also an Alaska State Trooper, reported that the accident pilot had arrived in Iliamna on Sunday, June 24, the day before the accident. He said that the accident flight was to serve as one of the accident pilot's orientation flights since he was unfamiliar with the Iliamna and King Salmon patrol areas. The first pilot added that soon after arriving in Iliamna, the accident pilot refueled his airplane.
The first pilot reported that on the day of the accident, the intended flight route was to depart Iliamna, fly to Igiugig, Alaska, proceed to the accident lake, and then return to Iliamna. The first pilot added that the accident lake had a remote cabin that is utilized by Fish and Wildlife Service enforcement officers during various sport fishing openings, and he wanted to acquaint the accident pilot with the cabin's location. He said that both airplanes arrived at the accident lake about 1840, and both pilots parked their airplanes on the lake, in front of the remote cabin. The pilots remained at the remote cabin for about 30 minutes, as the first pilot acquainted the accident pilot with the cabin. About 1910, both pilots boarded their respective airplanes, and prepared for the return flight to Iliamna. The first pilot said that he started his airplane's engine first, and started a slow taxi to the end of the lake, in preparation for a westerly departure. As he started his takeoff run, he noted that the accident pilot was in the process of starting his airplane's engine. The last time that the first pilot observed the accident airplane, the airplane was slowly taxiing to the end of the lake in preparation for a westerly departure.
As the first pilot flew back to Iliamna, he said that he tried to call the accident pilot on the radio, but was unable to establish radio contact. After arriving in Iliamna, he waited at the parking area for the second pilot to arrive. He said that he waited for about one hour, and then elected to retrace the accident pilot's anticipated flight path. He located the accident site, about a quarter-mile southeast of the departure lake.
Prior to the accident, the first pilot recalled having a brief conversation with the accident pilot concerning the use of the Cub Crafters main fuel valve installed in the accident airplane. He said that the accident pilot commented that he was not flying the airplane normally assigned to him, since his airplane did not have floats installed. He added that the airplane that the accident pilot normally flew had the original Piper main fuel tank selector valve installed. The accident pilot told the first pilot that he was unsure if the accident airplane's fuel selector valve should be operated in the BOTH position or the LEFT or RIGHT positions. The first pilot reported that since his airplane was equipped with the standard Piper fuel system as well, he was also unsure as to the operation of the accident airplane's fuel system.
The pilot held a commercial pilot certificate with airplane single-engine land, airplane multiengine land, and airplane instrument ratings. The pilot held an airplane single-engine sea rating, but was limited to private privileges. He also held a commercial helicopter, and instrument helicopter ratings. The most recent second-class medical certificate was issued to the pilot on April 12, 2001, and contained the limitation that corrective lenses be worn while exercising the privileges of his airman certificate.
According to the pilot/operator report (NTSB form 6120.1/2) submitted by the supervisor of the State of Alaska's aircraft section, the pilot's total aeronautical experience consisted of about 4,250 hours, of which 630 were accrued in the accident airplane make and model. In the preceding 90 and 30 days prior to the accident, the report lists a total of 40 and 20 hours respectively. No other personal flight records were located for the accident pilot.
According to pilot records provided by the supervisor, the pilot completed his annual proficiency check ride on December 4, 2000. The check ride was accomplished in another Piper PA-18-150, N5141T, which had the original Piper fuel system and fuel selector valve installed.
The airplane had accumulated a total time in service of 9,770.0 hours. Examination of the maintenance records revealed that the most recent annual inspection of the airframe and engine was accomplished on March 26, 2001, 80.9 hours before the accident.
The engine maintenance records note that the engine was installed new in the accident airplane on September 27, 1993, 1,533.3 hours before the accident.
Further examination of airframe maintenance records revealed that between January 1999, and October 1999, the accident airplane underwent an extensive airframe overhaul. During the overhaul process, a Cub Crafters, model 103700 fuel system kit was installed in accordance with an approved Federal Aviation Administration (FAA) supplemental type certificate (STC) number: SA00415SE. The Cub Crafters fuel system allows the pilot to select both fuel tanks at once, an option that is not available on the factory installations.
The original Piper PA-18 fuel system uses two 18 gallon, wing-mounted fuel tanks. The two wing tanks supply fuel to the engine via two header tanks to ensure adequate fuel flow to the carburetor during prolonged periods of uncoordinated flight. By installing the Cub Crafters model 103700 fuel system kit, the same 18-gallon fuel tanks are used, but the two header tanks are removed. In addition, the main fuel tank selector valve is replaced, or the existing fuel valve may be retrofitted and reinstalled for use with the new fuel system.
The original PA-18 main fuel tank selector valve has three positions available. If the selector is set to the LEFT tank, fuel is supplied to the engine from the left fuel tank. If the selector valve is set to the RIGHT tank, fuel is supplied to the engine from the right fuel tank. The third position is, OFF, which shuts off all fuel to the engine.
The Cub Crafters main fuel tank selector valve has four positions available. If the selector is set to the LEFT tank, fuel is supplied to the engine from the left fuel tank. If the selector valve is set to the RIGHT tank, fuel is supplied to the engine from the right fuel tank. If the selector valve is set to the BOTH position, fuel is supplied to the engine from both fuel tanks. The fourth position is, OFF, which shuts off all fuel to the engine.
A review of the aircraft flight logs recovered from the accident airplane, noted that on June 24, the accident pilot purchased 31.0 gallons of fuel. The recording engine tachometer reading at that time was 362.3. The engine tachometer reading at the accident site was 364.2, indicating 1.9 hours of elapsed flight time. A technical representative from Cub Crafters reported that the average fuel burn rate for the accident airplane's engine is 9.0 gallons per hour, with 17.2 gallons usable fuel in either the left or right fuel tanks. Based on this data, if only one fuel tank was utilized, the remaining fuel would have been about .1 gallons.
The FAA approved Cub Crafters STC requires the addition of a placard, placed just above the main fuel valve, which states: "TAKE OFF AND LANDING ON BOTH ONLY." The accident airplane complied with the addition of the placard.
In addition, the FAA approved Cub Crafters STC requires the placement of two additional placards, positioned adjacent to the left and right tank indicators, stating: "17.2 GALS USABLE." The accident airplane did not have the two additional placards installed, as required by the STC. The supervisor for the State of Alaska's aircraft section reported a discrepancy with installation instructions for the Cub Crafters fuel system. He said that the discrepancy concerned the placement of the required placards following the installation of the fuel system.
Further review of the Cub Crafters fuel system STC installation instructions revealed that the instructions concerning the addition and placement of placards, state: "Modify and placard the selector cover plate as shown in Cub Crafters' drawing number 101716 and 101718." These drawings provide detailed instructions concerning the placement of the required placards. However, drawing number 101700, also included in the Cub Crafters fuel system STC instructions, depict placards that read: "Right 18 Gals" and "Left 18 Gals," respectively. In a brief phone conversation with a technical representative from Cub Crafters, he reported that drawing number 101700 was a "systems drawing only" and was not intended to provide instructions for the placement of placards. He added that the replacement of the placards is outlined in the STC instructions. The technical representative added that effective immediately, and to eliminate any possible confusion in the future, drawing number 101700 will be changed to consistently depict the correct placards for the Cub Crafters fuel system.
The closest official weather observation station is Iliamna, which is located about 45 nautical miles southeast of the accident site. At 1953, an Aviation Routine Weather Report (METAR) was reporting in part: Wind, 310 degrees (true) at 9 knots; visibility, 10 statute miles; clouds and sky condition, clear; temperature, 62 degrees F; dew point, 44 degrees F; altimeter, 30.22 inHg.
There were no reports of communications with the accident airplane.
WRECKAGE AND IMPACT INFORMATION
The National Transportation Safety Board investigator-in-charge examined the airplane wreckage at the accident site on June 26, 2001. All of the airplane's major components were found at the main wreckage area.
The airplane came to rest upright in an area of soft, tundra-covered terrain. The nose of the airplane was oriented on a 230-degree magnetic heading. The fuselage of the airplane was observed in a 40-degree nose down attitude.
Two ground scars were present in the soft tundra, just aft of each float, measuring about 1 foot in length.
Flight control system cable continuity was established from each control surface to the cabin/cockpit area.
Both wings were broken at their inboard attach points, and displaced downward. Both lift struts remained attached to their respective wing and lower attach points.
The floats were torn from their respective fuselage attach points. The forward nose compartment of each float assembly was crushed and buckled upward.
The vertical stabilizer, horizontal stabilizer, rudder, elevator, and fuselage, aft of the cabin area, had minor damage. The flight control surfaces remained connected to their respective attach points. The stabilizer trim setting was found in the neutral position.
The propeller assembly remained connected to the engine crankshaft. The propeller blades each had minor aft bending, with minor leading edge damage.
The engine sustained impact damage to the lower front portion of the engine. The crankshaft could be rotated by the propeller. Gear and valve train continuity was established, and thumb compression in each cylinder was noted when the crankshaft was rotated by hand.
The fuel selector valve was selected to the LEFT fuel tank setting.
The right wing-mounted fuel tank remained intact, and was not damaged or breached. The left wing-mounted wing tank sustained a 1-inch puncture to the inboard portion. The left wing came to rest with the outboard portion positioned lower than the inboard portion, with no evidence of a postimpact fuel tank leak. An examination of the left fuel tank contents revealed that the left fuel tank appeared to be empty, with the exception of residual amounts of fuel in the outboard or lower portion of the fuel tank. The right fuel tank appeared to be full.
The left magneto switch was found in the ON position, and the right magneto switch was found in the OFF position.
Following recovery of the airplane, an additional wreckage examination was conducted at the State of Alaska's maintenance facility located at Lake Hood Seaplane base, Anchorage, Alaska. No preaccident mechanical anomalies were revealed during the examination.
On July 23, 2001, an engine examination and disassembly was conducted at Alaskan Aircraft Engines, Inc., Anchorage. No preimpact mechanical anomalies were noted during the examination of the engine, or engine accessories.
MEDICAL AND PATHOLOGICAL INFORMATION
A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 5700 E. Tudor, Anchorage, Alaska, on June 27, 2001. The cause of death for the pilot was attributed to multiple blunt force impact.
A toxicological examination was conducted by the FAA's Civil Aeromedical Institute (CAMI) on August 17, 2001, and was negative for any alcohol or drugs.
The supervisor for the State of Alaska's aircraft section reported that at the time of the accident, the Department of Public Safety operated twenty-three Piper PA-18's. He added that the long-term goal was to retrofit the entire fleet of Piper PA-18's with the Cub Crafters fuel system. At the time of the accident, only three PA-18's had the Cub Crafters fuel system installed.
A review of the State of Alaska, Department of Public Safety's "aircraft manual," which outline general operating policies and standards, revealed no provisions for differences training for the two fuel systems being utilized with the PA-18 fleet.
No parts or components were retained by the Safety Board.