Accident Summary
On June 18, 2009, about 1030 eastern daylight time, a Schweizer 269C-1 helicopter, registration N9421K, was substantially damaged during a forced landing near Naples Municipal Airport (APF), Naples, Florida. The aircraft was registered to North Bay Enterprises, Inc. and operated by Ocean Helicopters, Inc. Visual meteorological conditions prevailed, and no flight plan was filed for the 14 CFR Part 91 instructional flight from APF to Immokalee Regional Airport, Immokalee, Florida. The commercial pilot, the sole occupant, was seriously injured. The flight had originated about one minute earlier.
The pilot reported that after receiving departure clearance, he initiated a hover at 5 to 7 feet above ground level and began a takeoff paralleling runway 14, climbing at 55 to 60 knots indicated airspeed with manifold pressure near 29 inches of mercury. The engine rpm was near the bottom of the green arc. He lowered the collective slightly to reduce manifold pressure and increase rpm; manifold pressure decreased but rpm did not increase. Applying throttle produced little response. He then heard an intermittent low-rotor-rpm warning horn and noted the engine sounded sluggish. He turned left to return to the airport and advised the tower at 1030:09. After applying full throttle, the low-rotor-rpm horn became steady, and the helicopter descended rapidly. He aimed for an unoccupied pool, closed the throttle, and lowered the collective. The helicopter contacted a wood trellis and a small building adjacent to the pool. The pilot was rescued by local fire rescue. He estimated about 10 to 20 seconds elapsed from the perceived loss of engine power to landing.
A pilot-rated witness reported the takeoff and departure appeared normal with no unusual movements.
Pilot Information
The 56-year-old pilot held a commercial pilot certificate with ratings for airplane single-engine land, multi-engine land, and instrument airplane, as well as a second-class medical certificate issued May 19, 2009, with a limitation for near vision glasses. According to the NTSB report, his total flight time was 1,423 hours, with 19 hours in the accident helicopter make and model, including 7 hours as pilot-in-command.
Aircraft Information
The helicopter was a Schweizer 269C-1, serial number 0153, manufactured in July 2003. It was powered by a Lycoming HIO-360-G1A engine rated at 180 horsepower, equipped with Slick magnetos (left: 4347, right: 4370). The engine was removed for major overhaul on October 1, 2008, completed November 11, 2008, and reinstalled on February 25, 2009, at a helicopter total time of 2,200.5 hours. At the time of the accident, the engine had accumulated approximately 124 hours since overhaul and about 29 hours since the last 100-hour inspection. The mechanic who performed the last inspections stated he did not inspect the magneto breaker points as specified in the engine manufacturer's guide; he also did not remove either magneto during the inspections.
Earlier that day, another pilot flew the helicopter for about 1.1 hours and reported normal performance.
Meteorological Conditions
A surface observation at Naples Municipal Airport at 0953 (about 37 minutes before the accident) recorded wind from 060 degrees at 5 knots, visibility 10 statute miles, few clouds at 5,000 feet, temperature 32°C, dew point 23°C, and altimeter setting 29.97 inches of mercury.
Wreckage Examination
The helicopter crashed in a residential area approximately 0.79 statute mile southeast of the departure airport center. It contacted a building and trellis adjacent to a community pool and came to rest upright. No pre- or post-crash fire occurred. The fuel tank was nearly full with no fuel contaminants. The throttle was found in the idle position, and the clutch actuator was normal for full engagement. Examination of flight controls, tail rotor drive, and main rotor drive showed no evidence of preimpact failure or malfunction.
Engine and Magneto Examination
After recovery, the engine was removed and inspected. The right magneto was installed but positioned against the counterclockwise stop, and its mounting flange was fractured. The magneto timing was approximately 50 degrees before top dead center (specification is 25 degrees). The left magneto was properly timed. The engine was placed on a test stand with a test club propeller and operated for about 5 minutes; magneto drops were approximately 100 rpm, and cylinder compression was satisfactory.
Further inspection revealed that incorrect gaskets (part number 62224 instead of LW-12681) were installed between each magneto drive adapter assembly and magneto flange. The right magneto drive coupling showed damage with shear lips on both ends. The left magneto securing nuts were under-torqued: upper nut 122 inch-pounds, lower nut 95 inch-pounds (specification 204 inch-pounds).
The right magneto was examined by the NTSB Materials Laboratory. Fracture surfaces indicated overstress separation initiating in the radius between the flange and body on the outboard surface, progressing inboard due to bending loads from the clamp. Clamping surface markings showed rotation of the magneto against the clamp blocks. An impact dent on the intact side indicated forceful counterclockwise rotation. A curvilinear dent and partial shearing fracture suggested the magneto had been axially misaligned (cocked) in the engine accessory crankcase pilot diameter and then shifted into proper alignment.