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N6288L accident description

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Tail numberN6288L
Accident dateSeptember 12, 1998
Aircraft typeGrumman American AA-1B
LocationYoder, CO
Additional details: None

NTSB description

HISTORY OF FLIGHT

On September 12, 1998, at 0945 mountain daylight time, a Grumman American AA-1B, N6288L, was destroyed following a loss of power and subsequent impact with terrain near Colorado Springs East Airport, Yoder, Colorado. The commercial pilot and his passenger were fatally injured. The aircraft was owned/operated by the pilot under Title 14 CFR Part 91. Visual meteorological conditions prevailed for the local flight which originated from Meadow Lake Airport, Falcon, Colorado, approximately 15 minutes before the accident. No flight plan had been filed.

According to fuel records at the Meadow Lake Airport FBO, the pilot last purchased fuel (15 gallons) on July 18, 1998. According to a witness, the pilot "normally topped off his fuel tanks whenever he purchased fuel." The pilot's flight logbook, dated July 18, 1998, indicated that the pilot flew 3 flights with different passengers (Experimental Aircraft Association, Young Eagles) totaling 1 hour. The time of day that he fueled his airplane or the time of day he flew his passengers could not be determined.

According to the pilot's mechanic, the airplane was taxied to his shop for its annual inspection on July 28, 1998. The mechanic reported that when the inspection work was completed, the airplane was ground run for approximately 10 minutes. The annual inspection was completed on August 23, 1998, and the pilot hangared the airplane; the mechanic endorsed the engine and airframe logbooks for the annual inspection on September 2, 1998. The mechanic reported that when the airplane left his shop, he estimated that it was 1/2 to 1/3 full of fuel.

According to a witness, on the day of the accident, the pilot arrived at the airport at 0730, and departed at 0800 for a flight around the traffic pattern. None of the witnesses on the ground were sure how long the pilot flew, or if he flew more than one traffic pattern. The mechanic that performed the annual inspection on the airplane stated that he believed this was the "post-annual test flight."

Another witness reported that the pilot took his first Young Eagle passenger for a ride (approximately a 22 nm loop, at approximately 1,000 feet agl), and returned to the field. The witness further stated that the pilot departed with his second Young Eagle passenger at approximately 0930. The wreckage was spotted on the ground by a Young Eagle passenger in another event-participating airplane at 1000.

PERSONNEL INFORMATION

According to FAA records, the pilot received his commercial pilots certificate on July 6, 1989. The pilot's flight logbook documented that he had completed his required FAA Part 61 flight review on June 26, 1998, and that he had accumulated an estimated 1,135 hours of flight experience by the time of the accident. His flight logbook further indicated that during the previous 12 months, he had flown 11 times for 22.8 hours of flight experience; during the previous 90 days, he had flown 6 times for 6.5 hours.

AIRCRAFT INFORMATION

The airplane was a propeller-driven, two seat airplane, which was manufactured by Grumman American in 1972. It was certificated for a maximum gross takeoff weight of 1,600 pounds. The airplane was powered by a Textron Lycoming O-320, four cylinder, reciprocating, horizontally opposed, carbureted engine which had a maximum takeoff rating of 150 horsepower. At the last annual inspection on September 2, 1998, the tachometer reading was 322.95, and the airframe had accumulated approximately 3,971 hours.

The airplane was originally equipped with a Textron Lycoming O-235 engine (108 horsepower). On November 11, 1991, a Textron Lycoming O-320 engine was installed per Supplemental Type Certificate SA2477SW, dated July 13, 1977 (see attached documents). The engine was supplied fuel from a two-cell fuel tank, the left and right tubular main wing spars, with each cell holding 11 gallons (useable) or 12 gallons (total). The fuel quantity was indicated by two vertical sight gauges located on the left and right cabin walls.

The airplane's wing flaps were electrically operated. The airplane's Owner's Manual recommended using full flaps for soft field landings.

METEOROLOGICAL CONDITIONS

At 1045, the weather conditions at Colorado Springs Municipal Airport (elevation 6,184 feet), 245 degrees for 14 nm from the accident site, were as follows: wind 150 degrees for 8 knots; visibility 10 sm; scattered clouds at 11,000 feet; temperature 75 degrees F.; dew point 52 degrees F.; altimeter 30.12 inches of mercury. A witness at the accident site reported that the sky was clear, the wind was calm, and the temperature was 80 F. The density altitude was approximately 8,479 feet.

WRECKAGE AND IMPACT INFORMATION

The airplane impacted the terrain in an open grass field (elevation 6,145 feet) approximately 2 nm southwest of Colorado Springs East Airport, Ellicott, Colorado (N38 degrees 52 minutes 26 seconds, W104 degrees 26 minutes 38 seconds). The airplane was found upright, oriented longitudinally 360 degrees, and pitched nosed down approximately 25 degrees with the spinner and 1 propeller blade buried in the soil (see photographs). The fuselage was bent, aft of the cabin seats, and the empennage was laying flat on the ground. The wings were found level, broken from the fuselage (but not separated from the fuselage), and swept forward approximately 10 degrees. The outboard ends of both main spar fuel tanks were broken off and there was no evidence that fuel was present at the time of impact (the first rescuers at the accident scene reported not seeing or smelling any fuel). There was no ground scar.

All the airplane's flight control components were accounted for and continuity was established to each. All 3 tricycle fixed landing gear were found bent aft. The electric operated flaps were found in the up position and the master switch was found in the off position. The engine was displaced aft into the firewall. The crankshaft was free to rotate and "thumb method" compression was found on all four cylinders. Valve continuity was confirmed and all aft accessory gears rotated. Both magnetos sparked at all towers during hand rotation. The throttle and mixture engine control levers were both found full forward.

All major components of the airplane were accounted for at the accident scene. There was no evidence of pre or postimpact fire. No preimpact engine or airframe anomalies, which might have affected the airplane's performance, were identified.

MEDICAL AND PATHOLOGICAL INFORMATION

An autopsy on the pilot was performed by Dr. David L. Bowerman, a forensic pathologist, with the El Paso County Coroner's office, Colorado Springs, Colorado, on September 13, 1998.

Toxicology tests were performed on the pilot by FAA's Civil Aeromedical Institute (CAMI) in Oklahoma City, Oklahoma. According to CAMI's report (#9800252001), the pilot's carbon monoxide and cyanide tests were not performed due to lack of suitable specimens, and no ethanol was detected in the urine. Several drugs and their derivatives were identified in the pilot's urine and liver fluid (see attached toxicology reports). The NTSB's Medical Officer, Dr. Mitchell A. Garber, stated that because blood was not available for analysis, it was therefore not possible to draw specific conclusions with regard to exactly when the pilot may have ingested the various medications, or whether he might have been impaired at the time of the accident. He did state that the presence of each of the drugs in the urine suggests that they were used within the previous few days. Dr. Garber stated the following:

1. Doxylamine is a sedating over-the-counter antihistamine, often used in sleep aids such as Unisom. It is one of the most sedating of the antihistamines. 2. Diphenhydramine is also an over-the-counter antihistamine, available in many multi-symptom cold and allergy preparations, often known by the trade name Benadryl. It commonly results in drowsiness, and has measurable effects on performance of complex cognitive and motor tasks. 3. Verapamil, often known by the trade name Calan, is a blood pressure medication approved for use by the FAA. 4. Dextromethorphan is an over-the-counter cough suppressant, available in a large number of preparations, including the multi-symptom cold relievers indicated above. 5. Pseudoephedrine is a common decongestant with a trade name Sudafed that is found in many over-the counter cold and allergy preparations, including the multi-symptom cold relief preparations indicated above. This drug has been shown to have stimulant effects. 6. Phenylpropanolamine is an over-the-counter decongestant, and it is also the metabolite pseudoephedrine. 7. Acetaminophen is an over-the-counter pain reliever, often referred to by one of its common trade names, Tylenol.

Dr. Garber further stated that the stimulating effects of the decongestants may have combined to mask the sedative effects of the antihistamines. He stated that "in addition to possible adverse effects of the medications, distraction or sensory disturbance as a result of the condition for which the drugs were ingested may have also played a role in the accident."

Dr. Taylor, an FAA regional flight surgeon, stated that he would "not recommend a pilot fly an airplane with this combination of medications in him."

TEST AND RESEARCH

The airplane's tachometer was recorded as 322.95 when its annual inspection was performed and documented on August 2, 1998. At the accident site, on September 12, 1998, the airplane's tachometer was reading 323.58, which is a difference of .63. According to a manufacturer of single engine mechanical tachometers, the Grumman single engine airplanes have their tachometer's set at 2300 rpm, i.e., when the engine is running at 2,300 rpm the tachometer recording of 1.00 is equal to 1 hour of clock time. Therefore, an engine running at 1,000 rpm, the tachometer would record .435 for every hour of clock time.

A representative of the engine manufacturer stated that the airplane's engine should have burned approximately 10 gallons per hour at 2,700 rpm and 7.5 gallons per hour at 2,200 rpm; no figures could be determined for ground operating rpms. The representative did say that the fuel burn rate would vary greatly depending on density altitude and pilot operating technique.

The airplane's Owner's Manual indicated that, in the case of an engine failure, the best glide speed of 89 mph be flown for best range. It further indicated that soft field landings should be made with wing flaps fully extended and that the flap-up stall speed was 64 mph.

ADDITIONAL DATA

The airplane, including all components and logbooks, was released to a representative of the owner's insurance company on September 21, 1998.

(c) 2009-2011 Lee C. Baker. For informational purposes only.