Wasilla, AK, USA
N701BX
ZENAIR LTD STOL CH 701
The commercial pilot and the pilot-rated passenger, a Federal Aviation Administration (FAA) inspector, were on a local flight in the pilot’s float-equipped experimental light sport airplane. The pilot was a light sport designated pilot examiner (DPE) and the purpose of the flight was for the FAA inspector to administer a recurring DPE flight proficiency flight check of the pilot. The airplane departed from a lake near the pilot’s residence and crashed on the lake’s perimeter road. A postcrash fire consumed the majority of the passenger cabin and the inboard portions of each wing. Impact damage was consistent with a near-vertical descent. The composite propeller was burned, however pieces of the propeller had fractured on impact and were found away from the wreckage, indicative of the engine producing power when it crashed. No evidence of any preimpact mechanical anomaly was discovered. A witness living on the lakeshore said the airplane was usually airborne when it passed his house, but on this departure the airplane was still on the water when it passed, and continued out of sight. There was a stand of trees, high brush, and a hill at the departure end of the lake, separating it from the road. There was no evidence that the airplane impacted the trees or the bank. The airplane's weight and balance was calculated using the pilot’s and passenger's weights noted on their FAA medical certificates, 7.5 gallons of fuel predicated on a one-hour flight and 30-minute reserve, and zero baggage weight. The airplane's empty weight, gross weight, and center of gravity (CG) limitations were derived from the accident airplane's maintenance logbooks. The engine’s fuel consumption was estimated from the engine manufacturer's specifications. Baggage weight used was zero, although remnants of fishing gear and other personal items were found in the burnt wreckage, and a survival kit as required by regulation. The airplane's estimated gross weight was 36 lbs over its maximum gross weight, and the center of gravity was near the forward CG limit. Witness statements and evidence suggest that the fire burned intensely for 30-40 minutes. A witness stated that the pilot and passenger were planning to take the airplane fishing after the flight check, which would have required an additional 1.5 hours flight time and additional fuel. It is likely the airplane had more than the minimal 7.5 gallons of fuel onboard used for the weight and balance calculation (it had a 27 gallon capacity), and probably had fishing and survival equipment as well, adding to its already over gross weight. The fact that the airplane took longer to become airborne than usual, and its over gross weight, suggest that the airplane was near the lake’s shoreline and close to rising terrain when it finally became airborne, requiring a steep climb attitude. The lack of evidence of any mechanical problems along with the airplane’s near vertical descent is consistent with a loss of control due to an aerodynamic stall shortly after liftoff.
HISTORY OF FLIGHT On July 14, 2009, about 0930 Alaska daylight time, a float-equipped amateur built Zenair STOL CH701 airplane, N701BX, was destroyed during impact with terrain and a postcrash fire, following an uncontrolled descent during takeoff/initial climb from Kalmbach Lake, about 5 miles northwest of Wasilla, Alaska. The airplane was being operated by the pilot as a visual flight rules (VFR) local flight under Title 14, CFR Part 91, when the accident occurred. The airline transport pilot and pilot-rated passenger received fatal injuries. Visual meteorological conditions prevailed, and no flight plan was filed. An on-site examination of the wreckage was made by the National Transportation Safety Board (NTSB) investigator-in-charge (IIC) on July 14. During the examination it was discovered that the passenger was an FAA inspector from Oklahoma City, Oklahoma, giving the pilot, who was an FAA designated pilot examiner (DPE), an annual proficiency checkride which was required to maintain his certification as a DPE. A witness at the site told the NTSB IIC that she had left her residence en route to town, and came upon the burning wreckage in the middle of the road leading to her residence. She returned to her residence and called 911. Another witness said he was familiar with the airplane, and had watched part of the accident takeoff. He said the airplane took an unusually long time to become airborne, but disappeared from his view prior to reaching the end of the lake. There were no witnesses to the actual impact. INJURY TO PERSONS Both the pilot and sole passenger were killed in the accident. DAMAGE TO AIRCRAFT The airplane was destroyed by impact with terrain and a postcrash fire. PERSONNEL INFORMATION The 72 year old pilot held an airline transport certificate with multi-engine land, and single-engine land and sea ratings. He also held a flight instructor certificate, flight engineer certificate, ground instructor certificate, and repairman experimental aircraft builder certificate. His most recent second-class medical certificate was issued on June 6, 2008, and contained a limitation for corrective lenses. No personal flight log books were discovered for the pilot. According to an application for an FAA medical certificate dated June 6, 2006, the pilot had 27,200 hours of flying experience. AIRCRAFT INFORMATION The accident airplane was an experimental amateur built, Zenair STOL CH 701/A. The airplane was originally completed and registered in 1990. The airplane was maintained by the pilot who held a repairman certificate for experimental amateur built aircraft. The last entry in the airplane's maintenance logbook was made on June 12, 2009, and indicated an overhauled engine had been installed, and that the airplane was safe for flight. The logbook entry also indicated that the total time on the airplane since manufacture was 529 hours. Additional logbook entries indicated that the airplane had been placed on floats September 19, 2006, and a weight and balance calculation was completed at that time. METEOROLOGICAL INFORMATION The closest weather reporting station was the automated weather station at Wasilla Airport, Wasilla, about 3 miles west of the accident location. The automated weather observation at 0956 ADT reported the wind as calm, visibility 10 statute miles, ceiling 2,500 feet overcast, altimeter 30.16 inches of mercury, temperature 57 degrees F, and dew point 53 degrees F. COMMUNICATIONS There were no known communications with the airplane. WRECKAGE AND IMPACT INFORMATION On July 14, 2009, the NTSB IIC, along with an FAA air safety inspector from the Anchorage Flight Standards District Office (FSDO), traveled to the accident site, and examined the wreckage. The accident site was in the center of a dirt road, with steep banks and trees on both sides of the road. The impact area was about 300 feet from the southwest end of the departure lake. There was no evidence of the airplane striking the surrounding trees or banks. At the accident site, the IIC noted that all the major components and control surfaces were present. A postcrash fire consumed the majority of the passenger cabin and inboard sections of each wing. The crush lines on the floats were consistent with a steep vertical descent, striking the ground with the left float first. The left wing had corresponding crush lines and damage. The fuselage forward of the empennage had been consumed in a postcrash fire as evidenced by pooled molten aluminum. Both wings lay on the left side of the wreckage relative to the fuselage centerline. The lift struts for both wings were attached at the fuselage and wing fittings. The left wing was folded aft alongside the empennage, and was resting on its leading edge. The right wing lay upside down perpendicular to the fuselage centerline. The tail section, including the rudder, horizontal stabilizer, and elevators, were damaged but intact. Control cable continuity from the ailerons, flaps, elevator, and rudder, were confirmed to the burned cabin area. An examination of the engine showed that portions of the cylinders and case were fractured, and had melted in the postcrash fire. The composite three-bladed propeller had burned in the postcrash fire, however pieces of the propeller were found in the brush on both sides of the road. One piece of a propeller blade, about 8-10 inches long, had leading edge damage, and had snapped off near the propeller hub. The fracture was perpendicular to the leading edge of the blade. A second fracture was found in the same piece aft of and perpendicular to the stainless steel leading edge. The airplane wreckage was moved to a hangar near Wasilla. No evidence of preimpact mechanical problems were discovered during the wreckage examinations. MEDICAL AND PATHOLOGICAL INFORMATION A postmortem examination of the pilot was conducted under the authority of the Alaska State Medical Examiner, 4500 South Boniface Parkway, Anchorage, Alaska, on July 15, 2009. The examination revealed the cause of death for the pilot was attributed to blunt force injuries to the body and thermal charring resulting from an airplane accident. The FAA's Civil Aeromedical Institute (CAMI) conducted a toxicological examination on August 28, 2009, which was negative for any alcohol or drugs. Twenty-eight per cent carbon monoxide was detected in the blood. TESTS AND RESEARCH A representative weight and balance was calculated by the IIC. The pilot's and passenger's weights were derived from current FAA medical certificate information. The airplane had a fuel capacity of 29 gallons, however only 7.5 gallons of fuel consistent with a one hour checkride and the 30 minute VFR fuel reserve required by federal air regulations was used for the calculation. The airplane's empty weight, gross weight, and center of gravity (CG) limitations were derived from the accident airplane's maintenance logbooks. The fuel burn was estimated from the engine manufacturer's specifications. Baggage weight was calculated at zero, although remnants of fishing gear and other personal items were found in the burnt wreckage. A survival kit is also required by regulation in the State of Alaska. According to the airplane's official weight and balance, the maximum gross weight for the airplane on floats was 1100 pounds, and the aft and forward center of gravity limits were 10 and 18 inches respectively. Loaded as discussed above, the airplane's gross weight was 1136 lbs, 36 lbs over the airplane's maximum gross weight with the pilot and passenger, minimum fuel for the mission, and no baggage. The center of gravity was within limits at 17.08 inches. A witness reported that the pilot and passenger were going fishing at a lake about 45 miles west of the departure lake at the completion of the checkride. The flight to and from the remote lake would require about 1.5 hours flight time, and an additional 7.5 gallons of fuel, adding an additional 45 pounds to the gross weight of the airplane. The weight of the fishing gear and survival gear is unknown. Witness reports of seeing smoke from the burning wreckage, evidence at the accident site, and fire department response time, indicated that the airplane burned intensely for 30-40 minutes.
The pilot's failure to maintain sufficient airspeed to avoid an aerodynamic stall during takeoff and his decision to fly the airplane over its allowable gross weight. Contributing to the accident was the airplane's excessive gross weight.
Source: NTSB Aviation Accident Database
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