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On April 28, 1996, approximately 0811 Alaska daylight time, a wheel equipped Cessna 150 airplane, N8115U, registered to and operated by the pilot, collided with trees on a mountain side near Palmer, Alaska. The personal flight, operating under 14 CFR Part 91, departed Birchwood, Alaska, for a local flight to the Knik Glacier area. No flight plan was filed and visual meteorological conditions prevailed. The certificated private pilot, the sole occupant, was fatally injured. The airplane was destroyed by impact forces.
There are no known witnesses to the airplane crash. However, during a telephone conversation with Mr. Terry Peterson on April 30, 1996, he stated he owns property near the crash site and on the morning of April 28, 1996, he heard an airplane flying toward his property. At 0811 he heard what he described as a small explosion and 2 to 3 seconds later the sound of an impact. He stated that the engine sounded normal until he heard the explosion.
DAMAGE TO AIRCRAFT
The airplane was destroyed by impact/descent forces sustained as the airplane passed through a stand of trees 8 to 12 inches in diameter. The airplane was separated into five main groups of wreckage which were scattered on the wooded knoll.
The 39-year old pilot was the holder of a private pilot certificate, number 439024110, with an airplane single engine land rating. The certificate was issued on October 11, 1991. He also held a second class medical certificate dated November 6, 1993. According to 14 CFR Part 61.23,
(b) A second-class medical certificate expires at the end of the last day of (2) The 24th month after the month of the date of examination shown on the certificate, for operations requiring only a private, recreational, or student pilot certificate.
The accident occurred on April 28, 1996, 5 months after the expiration of the pilot's medical certificate.
The pilot was issued a Statement of Demonstrated Ability for defective distant vision poorer than 20/200 corrected to 20/20 bilaterally. His medical certificate required that he wear corrective lenses for near and distant vision. The Statement of Demonstrated Ability waiver was issued on January 9, 1992, under waiver number 10D19225.
According to information from the pilot logbooks, provided by the family, the pilot had a total flight time of 729.6 hours. The last entry in the pilot's logbook was dated April 27, 1996, the day before the accident. The next previous entry in the logbook was dated October 26, 1995. A review of the logbook to January 1, 1995, showed that all the flight time logged by the pilot was in the accident airplane, N8115U, which was 121.4 hours.
The logbook showed that the pilot received a biennial flight review on December 24, 1991, 52 months prior to the accident. The entry shows that he met the requirements satisfactorily on that date. According to 14 CFR Part 61.56,
(c) Except as provided in paragraphs (d) and (e) of this section, no person may act as pilot in command of an aircraft unless, since the beginning of the 24th calendar month before the month in which that pilot acts as pilot in command, that person has -
(1) Accomplished a flight review given in an aircraft for which that pilot is rated by an appropriately rated instructor certificated under this part or other person designated by the Administrator; and (2) A logbook endorsed by the person who gave the review certifying that the pilot has satisfactorily accomplished the flight review.
The airplane, N8115U, was a Cessna 150M airplane. The engine tachometer at the accident site showed that the airplane had a total flight time of 4,443.7 hours at the time of the accident. The airplane's records show that an annual inspection was completed on December 1, 1992, 40 months prior to the accident. At the time of the annual inspection the airplane had a total time of 4002.0 hours. According to 14 CFR Part 91.409,
(a) Except as provided in paragraph (c) of this section, no person may operate an aircraft unless, within the preceding 12 calendar months, it has had - (1) An annual inspection in accordance with part 43 of this chapter and has been approved for return to service by a person authorized by 43.7 of this chapter; or (2) An inspection for the issuance of an airworthiness certificate in accordance with part 21 of this chapter.
No inspection performed under paragraph (b) of this section may be substituted for any inspection required by this paragraph unless it is performed by a person authorized to perform annual inspections and is entered as an "annual" inspection in the required maintenance records.
The airplane was converted from a fixed tricycle gear configuration to a fixed gear, tailwheel configuration under Supplemental Type Certificate SA 2846 SW on November 18, 1993
The airplane was equipped with a continental O-200-A48 engine, serial number 230893.R, rated at 100 horsepower. The records showed that the engine was overhauled and installed in the airplane on December 1, 1992. The engine had a total time of 2,612 hours since overhaul.
A review of the engine logbook showed that no other maintenance was accomplished by a certificated airframe and powerplant mechanic. There are 15 entries between the Dates of December 1, 1992 and September 23, 1995, showing that work, ranging from oil changes to spark plug cleanings, was accomplished by the pilot.
There are no meteorological reporting stations near the accident site. However, the weather described by witnesses and observed by this investigator showed that it was clear. The visibility was 50 miles. The outside air temperature was estimated to be 45 degrees. There was no wind in the area. According to the sunrise, azimuth and elevation information, sunrise occurred at 0501. At the time of the accident, the sun was on a 100 degree bearing from the accident site and was at an inclination of 21.8 degrees. This placed the accident site in the shadow of a mountain.
AIDS TO NAVIGATION
The flight route of the airplane was not along any navigable airway. The closest navaid available to the pilot was the Big Lake VOR (very high frequency omnirange) located approximately 25 nautical miles west of the accident site.
WRECKAGE AND IMPACT INFORMATION
The accident site was located on the northwest side of a mountain at geographic coordinates 61 degrees, 29 minutes north, and 149 degrees, 06 minutes west. The accident site elevation was approximately 800 feet above mean sea level. The wreckage was located on top of a small mountain knoll along a ridge which extended along a magnetic bearing of 300 degrees. Broken tree tops and tree strikes aligned with the main wreckage on a magnetic bearing of 242 degrees. The knoll was wooded with many pine trees that were estimated to be 50 to 75 feet in height. The diameter of the trees ranged from 8 to 12 inches. The slope of the knoll measured 27 degrees near the top and the lower portion measured 35 degrees. The horizontal distance between the observed initial tree impact and the final impact, located on a tree 15 feet above the ground, was measured at 59 feet. The angle of descent from the initial to final impact mark was 30 degrees. The main airplane wreckage, consisting of the cockpit and engine compartment, came to rest at the bottom of the tree described as the final impact point along the flight path.
The airplane wreckage was separated into five main groups. The outboard portion of the right wing was located 70 feet downslope, measured along a 35 degree slope, from the initial tree strike along the 242 degree crash path. The tail section, consisting of the horizontal stabilizer, elevators, vertical fin, and rudder were located 69 feet beyond the outboard section of the right wing on a bearing of 208 degrees. The bearing from the tail section to the cockpit/engine section was 242 degrees. The next two groups of wreckage, (1) left wing, left lift strut, left aileron, left flap, and left cockpit door, and (2) the fuselage/empennage section from the baggage compartment aft to a point just forward of the vertical fin, were located to the right and downhill of the wreckage path.
MEDICAL AND PATHOLOGICAL INFORMATION
According to the Federal Aviation Administration's (FAA) Toxicological and Accident Research Laboratory, the toxicological report showed no alcohol, cyanide, or volatiles in the pilot's urine or blood. However, the tests did show that Oxymetazoline was detected in the urine. According to the FAA, Alaska Regional flight Surgeon's Office, that substance is commonly used in nasal sprays.
TEST AND RESEARCH
The airplane wreckage was examined on site. Due to the amount of damage, flight control continuity could not be established.
The engine was removed from the site and delivered to Seair Inc., of Anchorage, Alaska, and was inspected on May 8, 1996. The following was observed. The left magneto was timed at 30 degrees and the right magneto was timed at 28 degrees. The proper timing should have been 24 degrees. The magnetos were removed and bench tested.
The left magneto, Slick Model number 4201, serial number 2020083 was tested first. The spark gap used for the bench test was 5 mm. During the test one spark plug lead would not fire with the 5 mm gap. The magneto was disassembled and the examination revealed the following:
1. The distributor gear electrode finger was loose on the shaft and would rotate 10 to 15 degrees in either direction. The finger would also move in and out on the shaft. 2. There were white sticky globules through out the magneto. 3. The "E-gap" was set prematurely and was described by the Seair Accessory Technician as firing early. 4. Water droplets were found inside.
The right magneto, Slick model number 4201, serial number 8090047, was bench tested. The 5 mm firing gap was used. This magneto was misfiring on every spark plug lead. The magneto was disassembled and the examination revealed the following:
1. The coil was cracked. 2. The carbon brush was worn beyond use. It was not touching the coil contact. 3. The coil contact was burned by electric arcing. 4. The points were pitted. 5. The distributor gear electrode finger was tight on the shaft, but the end of the finger was unevenly burned. 6. The capacitor was checked and did not measure within limits.
A compression check was accomplished on the engine and the lowest compression noted after 80 pounds of pressure was introduced into the cylinder was 64 pounds.
The engine oil screen was examined and it was clear of any metal.
The time of the accident was determined by the information given by Mr. Terry Peterson listed under the witness section of this report and the information provided by the accident pilot's family. The family stated that the pilot was going to attend a church service which began at 1100. They found his clothes laid out on the bed and they had not been worn.
A review of the accident site and surrounding area showed that a forced landing area was available to the right side of the airplane's flight path. The forced landing area was a large sandbar on the Matanuska river located approximately 1/2 mile away (measured on an aeronautical chart) on a bearing of 320 degrees from the accident site.
According to the Cessna 150 Pilot Operator's Handbook, under emergency procedures, it states that after an in-flight engine failure, the best glide speed should be established as quickly as possible. While gliding to a suitable landing area, an effort should be made to identify the cause of the failure. The maximum glide chart indicates that to glide a distance of 1/2 mile, approximately 500 feet of altitude is needed.