NTSB Factual Report

On August 24, 2004, about 1500 eastern daylight time, a Robinson R-22, N4062X, registered to Airman Testing and Training Inc. and operated by Palm Beach Helicopter, as a Title 14 CFR Part 91 instructional flight, crashed during an autorotation in West Palm Beach, Florida. Visual meteorological conditions prevailed and no flight plan was filed. The commercial-rated certified flight instructor and student pilot received minor injuries, and the helicopter incurred substantial damaged. The flight originated from the Palm Beach County Park Airport, West Palm Beach, Florida, earlier that day, about 1415.

According to the flight instructor, the student pilot was practicing autorotations with the instructor at an indicated altitude of from 1,500 to 500 feet. The flight instructor decided to fly back to their departure airport, and while doing so the flight instructor idled the helicopter engine to simulate an engine out for the student pilot. When the student pilot went to recover from the simulated engine out, the helicopter engine did not respond to any power inputs. The flight instructor heard the low RPM horn, and took over the flight controls of the helicopter. The instructor proceeded to re-enter autorotation, flared, leveled the helicopter, and landed in an uneven field. The helicopter came to rest on its side.

The student pilot stated that he had been practicing autorotation procedures with his flight instructor. At an indicated altitude of about 500 feet and 70 knots indicated airspeed. They preformed a simulated engine out, procedure by applying, down collective, aft cyclic, throttle off, and entered autorotation. When they approached 150 feet indicated altitude, the student pilot went to apply engine power and said, "the engine was not there". The helicopter, was leveled before landing "hard" and "rolled" over multiple times. They both exited the helicopter unassisted.

After recovery, the helicopter engine was operated while on the helicopter airframe with FAA oversight. It was determined that the helicopter engine should be removed from the helicopter airframe and operated on a test stand for further analysis. The helicopter engine was removed from the airframe and taken to a certified engine overhaul facility with NTSB and FAA oversight. The helicopter engine was placed on a test stand and was operated through several parameters, engine start, magneto check, and a series of several rapid throttle advancements from idle, to full engine power. No abnormalities were noted with the test. A differential compression check was conducted and the following compressions were recorded: Cylinder one, 15/80 PSI, cylinder two, 15/80 PSI, cylinder three, 20/80 PSI, cylinder four, 15/80 PSI.

The cylinders were removed, and sent to ECI, Engine Components Inc., for further examination of the pistons and cylinders, with FAA oversight. The cylinders were visually inspected and pressure checked. Light exhaust valve/seat leakage was apparent on all four cylinders, while light intake valve/seat leakage was noted on the number two, and four cylinders. No cracks were detected on any of the cylinders. Pistons, pistons pins, and combustion chambers of all four cylinders displayed discoloration, typical of high engine temperature operation. The piston heads, and combustion chambers exhibited an unusually thick combustion product residues on all four cylinders. Discoloration of all cylinders and components were consistent with high engine temperatures.

One of the cylinders, was sent to the NTSB Materials Laboratory in Washington, DC for further examination of the deposits on the piston heads. Using an Energy Dispersive Spectrometer (EDS) for an analysis of the deposits, revealed that the deposits on the piston head consisted mostly of carbon with phosphorus, lead and bromine.

The operator of the helicopter stated the engine on the accident helicopter had accumulated 2611.8 total time in service, 612.6 hours since last overhaul, and 96.2 hours since last inspection at the time of the accident.

The helicopter was released by NTSB to the helicopter owner on September 17, 2004. Components retained by NTSB for further testing were released to the helicopter owner on April 12, 2005.

NTSB Probable Cause

The partial loss of engine power due to low cylinder compression during recovery from a practice autorotation resulting in a hard landing and damage to the helicopter.