NTSB Factual Report

On May 25, 2004, about 1815 Alaska daylight time, an amphibian float equipped Cessna 185 airplane, N70233, sustained substantial damage when it collided with a power line and an unoccupied residence during an emergency landing after takeoff from Merrill Field Airport, Anchorage, Alaska. The accident site was located in a mix of residential and commercial buildings, about 1/2 mile west-southwest of Merrill Field. The private pilot/airplane owner and the airline transport pilot-rated passenger received minor injuries. No one on the ground was injured. The airplane was being operated as a local personal flight by the pilot/owner under Title 14, CFR Part 91. Visual meteorological conditions prevailed, and no flight plan was in effect.

An on-site investigation and interviews with the pilot and passenger were conducted by NTSB investigators commencing about 1900. Additional interviews were conducted with the pilot and the passenger at various times during the ensuing investigation. The pilot related that he had purchased the airplane April 20, 2004, and the purpose of the flight was to become familiar with the airplane's handling characteristics and performance. He intended to perform at least one touch and go landing, and then leave the traffic pattern and fly to the local practice area. He estimated that there was 70-80 gallons of fuel aboard, and that the airplane was slightly below its gross weight limitation. He noted he drained the fuel tank sumps for contaminates, and discovered none. The rest of the preflight inspection and engine run-up were normal. The pilot indicated he was familiar with other Cessna 180 and 185 series airplanes, but had never flown a Cessna 180 or 185 on amphibian floats. He said he selected 20 degrees of flap as recommended, and that the airplane accelerated and climbed slower than he had anticipated during the takeoff roll and initial climb. He said he confirmed that the engine was developing full power, but as the airplane reached an altitude of about 400 feet above the ground, he was unable to get the airplane to climb higher. He indicated that while it appeared the engine was producing full power, the airplane was extremely sluggish, and it started to descend gradually. He was unable to find any suitable landing area, and attempted to land on a city street. Prior to reaching the street, the airplane collided with a power line, a tree, and the roof of an unoccupied two-story residence. The airplane came to rest inverted, on the driveway in front of the residence at 727 East 15th Avenue.

An examination of the airplane's flight controls and structure was completed on May 27 by the NTSB investigator-in-charge (IIC), two FAA aviation safety airworthiness inspectors, and another NTSB investigator. No evidence of any preimpact mechanical irregularities were discovered. The accident airplane's engine and propeller assembly were removed for further inspection and testing.

A propeller disassembly and inspection was performed under the direction of the NTSB IIC on June 7, at a propeller overhaul facility in Anchorage. Present at the inspection was a party representative from the airplane's engine manufacturer, Teledyne Continental Motors (TCM). Prior to the disassembly, it was noted that one of the two propeller blades had approximately 9 inches missing from its tip. The propeller's fracture surface was parallel to the chord, and was evenly colored and granular in appearance. Both blades displayed chord-wise scratching and leading edge gouges. The inspection disclosed no evidence of any preimpact mechanical anomalies with the propeller or propeller assembly.

On June 8, the engine was placed on a test stand at an engine overhaul facility in Anchorage. In addition to the NTSB IIC, the TCM party representative was there, as was an aviation safety inspector from the Anchorage FAA Flight Standards District Office. Prior to the attempt to run the engine, the fuel injection distributor manifold valve was opened and examined. Water, estimated to be about a teaspoon, was present in the manifold cavity, as was rust and other particulate matter in the manifold screen. Approximately 75 per cent of the screen was occluded by the particulate matter/rust. The screen was cleaned and replaced. The engine driven fuel pump was also disassembled, and signs of rust and residual amounts of water were found. The pump was cleaned, reassembled, and placed on the engine. The fuel controller's inlet finger screen was about 90 per cent occluded with a white, viscous substance. The screen was cleaned, and the unit returned to its housing.

The engine started normally on two occasions with a club test propeller installed, but would not accelerate beyond 2,100 rpm. The number 4 cylinder was cool to the touch, and a differential pressure test was accomplished on all six cylinders, with the following results: Number 1, 71/80; Number 2, 68/80; Number 3, 69/80; Number 4, 76/80; Number 5, 69/80; Number 6, 68/80. The number 4 cylinder's spark plugs were examined, and appeared to be worn excessively. The spark plugs were replaced with new spark plugs, and the engine was started again. All six cylinders became hot to the touch, and the engine readily accelerated to 2,500 rpm, with an indicated fuel flow of 28 gallons per hour.

The airplane had accrued approximately 14 service hours since the last annual inspection on May 1, 2003. In the preceding 2.5 years, the airplane had accrued about 58 total service hours. Federal aviation regulations specify that an annual inspection is valid until the last day of the month in which it was issued, thus the annual inspection was still valid at the time of the accident. The pilot/owner of the airplane stated that he had intended to have an annual inspection performed prior to the accident flight, but the shop he wished to use was unable to schedule it until May 31. He stated that the airplane did not have a prepurchase inspection.

Federal air regulation section 91.7, Civil Aircraft Airworthiness, states, in part: "(A) No person may operate a civil aircraft unless it is in an airworthy condition. (B) The pilot in command of a civil aircraft is responsible for determining whether that aircraft is in condition for a safe flight. The pilot in command shall discontinue flight when unairworthy...conditions occur. "

NTSB Probable Cause

The pilot/owner's failure to ensure that the airplane was in an airworthy condition prior to flight, which resulted in a partial loss of engine power and subsequent in-flight collision with a residence during an emergency landing after takeoff. Factors associated with the accident are a contaminated fuel pump, a flow-restricted fuel controller, a flow-restricted distributor valve, worn spark plugs, and inadequate servicing/maintenance of the airplane by other maintenance personnel.