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On May 22, 2008, at 1158 eastern daylight time, a Grumman American AA-1C, N9555U, was substantially damaged when it impacted a parked trailer, shortly after takeoff from Northeast Philadelphia Airport (PNE), Philadelphia, Pennsylvania. The certificated flight instructor (CFI) and certificated student pilot were killed. The airplane was operated by a flight school and based at PNE. Visual meteorological conditions prevailed, and no flight plan was filed for the local instructional flight which was conducted in accordance with Title 14 Code of Federal Regulations Part 91.
According to air traffic controllers at PNE and recorded voice communications, the accident airplane was in the left traffic pattern for runway 33, practicing touch-and-go landings. There were two other aircraft in line to land after the accident airplane; however, both of these aircraft were in the right traffic pattern. A helicopter was also in position for takeoff at the intersection of taxiways "Gulf" and "Juliet," and the helicopter pilot was instructed to hold his position until the accident airplane landed.
As the accident airplane touched down on runway 33, the controller informed the helicopter pilot that the accident airplane would be in a "left downwind departure" and he was cleared for takeoff. As the helicopter departed to the west, and the accident airplane was climbing after landing, the controller instructed, "five five uniform make right traffic."
The accident pilots did not acknowledge the instruction, but according to the controllers, the airplane appeared to immediately bank "hard right" at an altitude of 200 feet. The airplane continued in a descending right bank until it impacted the ground.
According to the helicopter pilot, he was in his helicopter at the intersection of taxiways "Golf" and "Juliet," facing the departure end of runway 33 when he observed the accident airplane. The airplane departed from runway 33, and appeared to climb “slowly.” At an altitude of approximately 200 feet, the airplane initiated a 10 to 20-degree right bank, and he noted that it “did not appear to be a coordinated turn.” He then observed the airplane’s bank increase to approximately 30 degrees, and then the wings “fluttered,” and the airplane “stalled.” The right wing and nose “dropped,” to an approximate 80 to 90-degree bank, and he lost sight of the airplane behind parked trailers. The helicopter pilot stated that there was a “lot of wind” at the time of the accident, but the winds were favoring runway 33. He thought the winds were from approximately 290 - 300 degrees at 15 – 20 knots. The helicopter pilot also confirmed that ATC informed him the airplane would be a “left downwind departure.”
Another witness was on the ramp at the airport preparing his airplane for a flight when he noticed a helicopter hovering off to the right of runway 33. He then observed the accident airplane takeoff. As the airplane passed the departure end of runway 33, at an altitude of approximately 200 feet, it appeared to "go vertical," and then "kicked hard right." The witness stated, "it looked like the takeoff stalls I would practice but they also had the right turn with the high angle of attack added in." After the airplane banked to the right, it "came down on an angle on its side," and disappeared behind a row of trailers. About 5 seconds later, the witness saw smoke and observed the helicopter hovering above the accident site.
The CFI, 28 years old, held a flight instructor certificate with ratings for airplane single-engine land and instrument airplane. He also held a commercial pilot certificate with ratings for airplane single and multiengine land, and instrument airplane. His most recent first-class medical certificate was issued on February 21, 2008. At that time, he reported 1,500 hours of total flight experience.
Examination of an insurance form provided by the flight school revealed that as of January 9, 2008, the flight instructor had accumulated 1,600 hours of flight experience as an instructor, and 800 hours of experience in the make and model of the accident airplane.
The student pilot's most recent second-class medical certificate was issued on May 9, 2007. At that time, he reported 20 total hours of flight experience.
According to records maintained by the flight school, as of May 10, 2008, the student pilot had accumulated approximately 87 total hours of flight experience, all of which was in the make and model of the accident airplane. The accident flight was to be the student pilot's last instructional flight prior to his private pilot check ride.
The airplane was manufactured in 1977 and equipped with a Lycoming O-235 engine.
Review of the airplane's maintenance records revealed that its most recent 100-hour inspection was performed on March 28, 2008 with no anomalies noted. The airplane had flown approximately 96 hours since the inspection.
The weather reported at PNE, at 1154, included wind from 310 degrees at 8 knots, 10 miles visibility with light rain, scattered clouds at 3,600 feet, and broken clouds at 4,300 feet.
At 1054, the winds were recorded from 270 degrees at 17 knots, gusting to 25 knots.
Northeast Philadelphia Airport was comprised of two crossing runways oriented in a 6/24 and 15/33 configuration.
The airplane impacted a parked trailer, at a warehouse located just off the departure end of runway 33, adjacent to the airport perimeter fence. Green paint transfer, consistent in color with the paint scheme of the accident airplane, was observed on the side corner of a parked trailer. An adjacent trailer, located approximately two feet from the impacted trailer, was not disturbed.
Approximately 14 feet from the trailer, an impact mark was observed in the pavement, with red paint transfer, consistent with the color of the propeller spinner. The wreckage path continued on an approximate 170-degree heading to the main wreckage. Remnants of the right wingtip light and sections of the Plexiglas canopy were observed along the wreckage path.
The airplane came to rest under a parked trailer, which was docked to a warehouse loading bay. The airplane remained relatively intact; however, it was almost completely consumed by a post-impact fire. All flight controls remained attached to their respective attachment points, and flight control continuity was confirmed from the controls to the cockpit.
The engine remained attached to the firewall; however, the propeller was separated from the engine, and located about 20 feet from the engine. One propeller blade exhibited a slight "S-bend", and the other blade was curled aft and exhibited severe chordwise scratching. The propeller spinner was observed severely dented and the curled blade was noted inside the spinner.
The engine was removed from the airplane and further examined. The engine could not initially be rotated due to impact damage on the number 1 cylinder. The cylinder was removed, and valve train continuity and thumb compression was confirmed on the remaining three cylinders.
The magnetos could not be tested due to fire damage. Examination of the spark plugs revealed the bottom number 1 and number 3 spark plugs were oil soaked. The remaining spark plugs revealed "normal to worn-out normal" when compared to the Champion "Check A Plug spark plug chart."
MEDICAL AND PATHOLOGICAL INFORMATION
The City Of Philadelphia's Medical Examiner's Office performed autopsies on both pilots. According to those reports, the cause of death for the student pilot was listed as cerebral injury and smoke and soot inhalation. The cause of death for the CFI was listed as blunt trauma and smoke and soot inhalation.
The FAA Bioaeronautical Research Laboratory, Oklahoma City, Oklahoma conducted toxicological testing on the pilots. According to the toxicological reports, 22% CARBON MONOXIDE and 1.2 ug/ml CYANIDE was detected in the student pilot's blood, and 17% CARBON MONOXIDE and 0.48 ug/ml CYANIDE was detected in the CFI's blood.
TESTS AND RESEARCH
Photographic evidence was recovered from a security camera at the warehouse where the airplane crashed. The camera captured five frames of the airplane, during a five second period. When the airplane came into view of the camera in the first frame, it was in a 90-degree right bank, oriented on an approximate heading of 330 degrees. In the second frame, the airplane was descending, still in an approximate 90-degree right bank. The third frame indicated the airplane had continued its descent and bank and was now oriented nose-down, on an approximate heading of 150 degrees, or 180-degrees from the orientation in the previous frame. This frame also showed the airplane striking a parked trailer with its right wing. The fourth frame displayed the airplane on the pavement between a row of parked trailers and the warehouse, in a level (flat) attitude. The last frame showed the airplane under another row of parked trailers which were docked to the warehouse.
FAA and Manufacturer Guidance
A review of FAA-H-8083-3, Airplane Flying Handbook, revealed:
"...At the same gross weight, airplane configuration, and power setting, a given airplane will consistently stall at the same indicated airspeed if no acceleration is involved. The airplane will, however, stall at a higher indicated airspeed when excessive maneuvering loads are imposed by steep turns, pull-ups, or other abrupt changes in its flightpath. Stalls entered from such flight situations are called "accelerated maneuver stalls..."
"...Failure to take immediate steps toward recovery when an accelerated stall occurs may result in a complete loss of flight control...
"...At any given airspeed, the load factor increases as angle of attack increases, and the wing stalls because the angle of attack has been increased to a certain angle...The speed at which a wing will stall is proportional to the square root of the load factor."
According to the load factor chart in FAA Advisory Circular 61-23C, Pilot's Handbook of Aeronautical Knowledge, a bank angle of 45 degrees will produce a load factor of 1.4, a bank angle of 60 degrees will produce a load factor of 2, and a bank angle of 80 degrees will produce a load factor of 6 (or 3 times the stalling speed).
A review of the "Stall Speeds" chart from the Grumman American AA-1C Pilot Operating Handbook (POH) revealed that in a flaps up configuration, the airplane would stall at the following speeds:
1) At a bank angle of 20 degrees, the stall speed would be about 65 mph
2) At a bank angle of 40 degrees, the stall speed would be about 72 mph
3) At a bank angle of 60 degrees, the stall speed would be about 90 mph
The POH listed a rotation speed between 60 and 65 mph and a normal climb speed of 95 mph.