N4SU

HISTORY OF FLIGHTOn June 10, 2016, at 1710 Pacific daylight time, a Grumman American Aviation Corporation AA-1B, N4SU, was destroyed when it impacted a residence shortly after takeoff from Jack Northrop Field/Hawthorne Municipal Airport (HHR), Hawthorne, California. The private pilot and flight instructor were fatally injured. There were no ground injuries. The airplane was registered to and operated by the pilot under the provisions of Title 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed for the instructional flight, and no flight plan was filed.

A mechanic at a fixed-base operator (FBO) at HHR stated that the pilot and the instructor met in the lobby of the FBO before proceeding to the airplane about 10 minutes later. He stated that the flight was part of a flight review. The mechanic stated that he was not familiar with the instructor and that the pilot typically flew alone. He observed the airplane take off and stated that he "knew something was wrong" when the airplane was about 3/4 of the way down the runway during the takeoff roll. As it neared the departure end of the runway, the airplane was "about at the roofline" of the surrounding buildings and in a nose-up attitude. He stated that the engine sounded "smooth" but like it was "at half power."

The tower controllers at HHR reported that the pilot phoned the tower to arrange for a no-radio departure using light gun signals. During this conversation, the pilot said that he had obtained the current automated weather information. The airplane taxied to runway 25, was issued a green light gun signal, and subsequently departed. The controllers observed the airplane become airborne, settle back onto the runway about 1,500 ft from its initial rotation point, and then become airborne again. The controllers stated that the airplane "remained low" as it climbed out.

A commercial pilot who was preparing to start his airplane at HHR stated that his attention was drawn to the accident airplane due to the "rough" sound of its engine, and he stated that its climb rate was "much lower" than that of a typical airplane on departure. He estimated its altitude at the departure end of the runway to be between 400 and 500 ft above the ground. He stated that the pilot appeared to be "trying to gain altitude by lowering the nose to gain airspeed and pitching up"; however, each time the airplane's nose rose, the airplane lost altitude. He then saw the airplane "steering around some palm trees to avoid a collision" before it disappeared from his view below trees and buildings. PERSONNEL INFORMATIONThe pilot, age 90, was the owner of the airplane. He held a private pilot certificate with ratings for airplane single- and multi-engine land, instrument airplane, and glider. His most recent Federal Aviation Administration (FAA) third-class medical certificate was issued on August 19, 2015, with a limitation for corrective lenses, and was not valid for any class after August 31, 2016. On the application for that certificate, the pilot reported 3,000 total hours of flight experience, of which 50 hours was flown in the previous 6 months.

The instructor, age 71, held an airline transport pilot certificate with ratings for airplane single- and multi-engine land, and a flight instructor certificate with a rating for airplane single-engine. His most recent FAA third-class medical certificate was issued in May 2016 with a limitation for corrective lenses. On the application for that certificate, he reported 18,000 total hours of flight experience, with 200 hours in the previous 6 months.

Personal flight logs were not recovered for either pilot. AIRCRAFT INFORMATIONThe airplane was manufactured in 1974 and registered to the pilot in December 2015. It was equipped with a 108-horsepower (hp) Lycoming O-235-C2C reciprocating engine. In June 2005, the airplane was equipped with a new propeller in accordance with a supplemental type certificate, which increased the engine power rating from 108 hp to 115 hp. The most recent annual inspection was completed in November 2015 at 1,724 hours total airframe time. At the time of the annual inspection, the engine had accumulated 1,724 hours since new and 611.6 hours since top overhaul. (At an unspecified time in 2001, the engine received 4 new cylinders, commonly referred to as a top overhaul.) The maintenance logbooks indicated that the airplane had accumulated about 39 hours of operation in the 26 months before this annual inspection. The airframe and engine times at the time of the accident could not be determined.

According to the maintenance logbooks, the engine had never been overhauled.

The total fuel on board the airplane at the time of the accident could not be determined. If the airplane had been fueled to capacity (24 gallons) before the flight, it would have been operating about 20 lbs under its maximum certificated gross weight of 1,560 lbs. At maximum gross weight, given the atmospheric conditions present at the time of the accident, the airplane's takeoff ground run distance would have been about 850 ft; its distance to clear a 50-ft obstacle would have been about 1,700 ft. METEOROLOGICAL INFORMATIONThe 1653 weather observation at HHR included wind from 270° at 8 knots, clear skies, 10 miles visibility, temperature 22°C, dew point 4°C, and an altimeter setting of 29.89 inches of mercury. AIRPORT INFORMATIONThe airplane was manufactured in 1974 and registered to the pilot in December 2015. It was equipped with a 108-horsepower (hp) Lycoming O-235-C2C reciprocating engine. In June 2005, the airplane was equipped with a new propeller in accordance with a supplemental type certificate, which increased the engine power rating from 108 hp to 115 hp. The most recent annual inspection was completed in November 2015 at 1,724 hours total airframe time. At the time of the annual inspection, the engine had accumulated 1,724 hours since new and 611.6 hours since top overhaul. (At an unspecified time in 2001, the engine received 4 new cylinders, commonly referred to as a top overhaul.) The maintenance logbooks indicated that the airplane had accumulated about 39 hours of operation in the 26 months before this annual inspection. The airframe and engine times at the time of the accident could not be determined.

According to the maintenance logbooks, the engine had never been overhauled.

The total fuel on board the airplane at the time of the accident could not be determined. If the airplane had been fueled to capacity (24 gallons) before the flight, it would have been operating about 20 lbs under its maximum certificated gross weight of 1,560 lbs. At maximum gross weight, given the atmospheric conditions present at the time of the accident, the airplane's takeoff ground run distance would have been about 850 ft; its distance to clear a 50-ft obstacle would have been about 1,700 ft. WRECKAGE AND IMPACT INFORMATIONThe airplane impacted a residence about 1 nautical mile west of HHR. The initial impact point was identified as an approximate 30-ft-tall palm tree about 40 ft east of the residence. The majority of the airplane's left wing came to rest under the tree and exhibited a concave depression consistent with the diameter of the tree. The main wreckage came to rest against the front of the residence and was consumed by postcrash fire. The empennage was suspended from the second-floor balcony, and the control cables remained attached to the main wreckage. Flight control continuity was established from the cockpit area to the rudder and elevator; however, continuity to the ailerons could not be established due to fire damage. The wing spar was fractured in several locations. No information could be obtained from the cockpit instruments.

The propeller remained attached to the engine at the crankshaft flange, and the engine remained attached to its mounts. One propeller blade exhibited slight s-bending and chordwise scratching; the second blade was relatively undamaged.

The engine was rotated by hand, and continuity of the valve and drivetrain was confirmed. Thumb compression was obtained on all cylinders. The carburetor was separated from the engine and sustained thermal damage. The float bowl was absent of fuel, and both metal floats were damaged. The magnetos and engine-driven fuel pump were significantly fire damaged and could not be tested further. The spark plugs were removed and displayed normal wear.

Disassembly and detailed examination of the engine's internal components revealed that the crankshaft was undamaged; however, all of the bearings displayed radial scoring. The tappet faces corresponding to the intake valves of all 4 cylinders displayed spalling, and the corresponding camshaft lobes were significantly worn. When measured with a caliper, the camshaft lobes corresponding to all 4 exhaust valves measured 1.400 inches. The lobe corresponding to the Nos. 1 and 2 cylinder intakes measured 1.275 inches, and the lobe corresponding to the Nos. 3 and 4 cylinder intakes measured 1.250 inches. ADDITIONAL INFORMATIONAccording to Lycoming Service Instruction SI1009AZ, "Recommended Time Between Overhaul Periods," the make/model engine installed on the airplane should be overhauled at 2,000-hour intervals or before the 12th year, whichever occurs first. The instruction further states:

Engine deterioration in the form of corrosion (rust) and the drying out and hardening of composition materials such as gaskets, seals, flexible hoses and fuel pump diaphragms can occur if an engine is out of service for an extended period of time. Due to loss of a protective oil film after an extended period of inactivity, abnormal wear on soft metal bearing surfaces can occur during engine start.

Lycoming Service Letter L180B, "Engine Preservation for Active and Stored Aircraft," states that, "Engines in aircraft that are flown only occasionally may not achieve normal service life because of corrosion. This occurs when moist...