History of Flight
On June 10, 2016, at 1710 Pacific daylight time, a Grumman American Aviation Corporation AA-1B, registration 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. No ground injuries occurred. The flight was conducted under 14 CFR Part 91 as an instructional flight for a flight review. Visual meteorological conditions prevailed, and no flight plan was filed.
A mechanic at a fixed-base operator observed the pilot and instructor meeting before proceeding to the airplane. He noted the airplane during takeoff: when it was about three-quarters down the runway, it appeared to be at rooftop height of surrounding buildings in a nose-up attitude. The engine sounded smooth but as if at half power.
Tower controllers reported that the pilot arranged for a no-radio departure using light gun signals. The airplane taxied to runway 25, received a green light, and departed. Controllers observed the airplane become airborne, settle back onto the runway about 1,500 ft from its initial rotation point, then become airborne again. The airplane remained low during the climb.
A commercial pilot preparing to start his airplane heard a rough engine sound from the accident airplane and noted its climb rate was much lower than typical. He estimated its altitude at the departure end of the runway at 400–500 ft. He saw the pilot lower the nose to gain airspeed and pitch up, but each pitch-up resulted in altitude loss. He then observed the airplane steer around palm trees before disappearing.
Personnel Information
The pilot, aged 90, held a private pilot certificate with ratings for airplane single- and multi-engine land, instrument airplane, and glider. His most recent FAA third-class medical certificate was issued on August 19, 2015, with a limitation for corrective lenses, and was not valid after August 31, 2016. On that application, he reported 3,000 total flight hours, with 50 hours in the previous 6 months.
The instructor, aged 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. He reported 18,000 total flight hours, with 200 hours in the previous 6 months.
Personal flight logs were not recovered for either pilot.
Aircraft Information
The airplane was manufactured in 1974 and registered to the pilot in December 2015. It was equipped with a 108-horsepower Lycoming O-235-C2C engine. In June 2005, a new propeller was installed per a supplemental type certificate, increasing engine power rating to 115 hp. The most recent annual inspection was completed in November 2015 at 1,724 total airframe hours. At that time, the engine had 1,724 hours since new and 611.6 hours since top overhaul. The engine had never been overhauled. The airplane had accumulated about 39 hours of operation in the 26 months before that annual inspection. Total airframe and engine times at the accident could not be determined.
The total fuel on board could not be determined. If fueled to capacity (24 gallons), the airplane would have been about 20 lbs under maximum certificated gross weight of 1,560 lbs. At maximum gross weight and given the atmospheric conditions at the time, takeoff ground run distance would have been about 850 ft; distance to clear a 50-ft obstacle would have been about 1,700 ft.
Meteorological Information
The 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.
Wreckage and Impact Information
The airplane impacted a residence about 1 nautical mile west of HHR. Initial impact was with an approximate 30-ft-tall palm tree about 40 ft east of the residence. The left wing came to rest under the tree with a concave depression. Main wreckage came to rest against the front of the residence and was consumed by postcrash fire. The empennage was suspended from a second-floor balcony. Flight control continuity was established from the cockpit to the rudder and elevator; continuity to the ailerons could not be established due to fire damage. The wing spar was fractured in several locations. Cockpit instruments yielded no information.
The propeller remained attached to the engine; one blade exhibited slight s-bending and chordwise scratching, the other was relatively undamaged. The engine was rotated by hand, confirming valve and drivetrain continuity. Thumb compression was obtained on all cylinders. The carburetor was separated and thermally damaged; the float bowl was absent of fuel, and both metal floats were damaged. Magnetos and engine-driven fuel pump were significantly fire damaged and could not be tested. Spark plugs displayed normal wear.
Disassembly revealed the crankshaft undamaged but all bearings displayed radial scoring. The tappet faces of intake valves on all four cylinders showed spalling; corresponding camshaft lobes were significantly worn. Exhaust valve lobes measured 1.400 inches; intake lobes for cylinders 1 and 2 measured 1.275 inches; for cylinders 3 and 4, 1.250 inches.
Medical and Pathological Information
An autopsy on the pilot determined cause of death as multiple blunt injuries, with atherosclerotic cardiovascular disease contributing. The heart weighed 660 grams and showed biventricular enlargement. The left anterior descending coronary artery was 80% stenosed; the right and circumflex arteries were 90% stenosed. Toxicology identified losartan, metoprolol, and sitagliptin, none considered impairing.
An autopsy on the instructor determined cause of death as flame burn injury and multiple blunt force injuries. The heart was severely enlarged and dilated, weighing 500 grams. The autopsy noted sternotomy wires from a previous procedure; the report described 80% stenosis of the right coronary artery and 30% stenosis of the circumflex. The right kidney was absent. Toxicology identified atorvastatin, cetirizine, hydroxyzine, warfarin, and tramadol (0.063 ug/mL). Cetirizine, hydroxyzine, and tramadol carry drowsiness warnings. The instructor's medical records indicated kidney failure (dialysis started in 2012), severe coronary artery disease with bypass graft in 2013, and other conditions. He had 18 daily medications, some potentially impairing. He did not report these conditions to the FAA.
Additional Information
Lycoming Service Instruction SI1009AZ recommends overhaul at 2,000-hour intervals or before the 12th year. It notes that engine deterioration can occur if an engine is out of service for an extended period, and abnormal wear on bearing surfaces can occur during engine start after prolonged inactivity. Lycoming Service Letter L180B states that engines in aircraft flown only occasionally may not achieve normal service life due to corrosion.