Cherry Point, NC, USA
N5234A
Grumman S-2B
The retired military airplane was on an approximate 3-mile final approach to the runway when it experienced a loss of power in the right engine. The crew chief entered the cockpit and pushed the power levers forward when the pilot flying (PF) called for full power. The flightcrew did not comply with the memory items, nor did they comply with the "challenge and reply items" on the airplane's checklist, but instead, the pilot not flying (PNF) feathered the propeller on the left (operating) engine based solely on the PF's comment that he was holding right rudder. When the PNF perceived the left engine slowing down, but no reduction in drag, he un-feathered the left propeller. During the subsequent descent, the airplane struck power lines, trees, terrain, and was destroyed in a postcrash fire ignited by the downed power lines. Examination of the wreckage revealed heavy gauge wire wrapped around the left propeller, with signatures consistent with operation at impact. Examination of the right engine revealed a seized, inoperative dual magneto.
HISTORY OF FLIGHT On May 3, 2007, at 1430 eastern daylight time, a Grumman S-2B, N5234A, was destroyed when it collided with power lines and terrain during a forced landing near Cherry Point Marine Corps Air Station (NKT), Cherry Point, North Carolina. The certificated airline transport pilot, commercial pilot, and the crew chief were seriously injured. Two passengers sustained minor injuries. Visual meteorological conditions prevailed for the flight that originated from Franklin Municipal Airport (FKN), Franklin, Virginia, at 1342, and destined for NKT. No flight plan was filed for the positioning flight conducted under 14 Code of Federal Regulations Part 91. The airplane was a retired military aircraft operated by the Commemorative Air Force. The purpose of the flight was to participate in an air show at the Marine Corps Air Station. During a telephone interview, the pilot reported that the flight to Cherry Point was uneventful, and that there were no problems with the performance and handling of the airplane. The airplane was established on a left base for landing on runway 5, about 1,000 feet, with the copilot at the flight controls. The airspeed was about 120 knots, the landing gear was down, the flaps were at the one-third setting, and the "rudder assist" was on. The pilot perceived a loss of engine power, but he could not determine which engine had lost power. The copilot called for full power, and the crew chief entered the cockpit and pushed the power levers forward, with no perceived increase in engine power. While the copilot was trying to figure out what was going on, the pilot feathered the left propeller. The airplane lost more engine power, so the pilot un-feathered the left propeller, as it was apparently not the correct one. According to the pilot's written statement, the airplane was established on a 3-mile final approach for landing on runway 5L, about 1,100 feet, with the copilot at the flight controls. The pilot perceived a loss of engine power, but he could not determine which engine had lost power. He asked the copilot which engine lost power, and the copilot replied that he was holding right rudder. The pilot then feathered the left propeller, noted that the left engine was slowing down, but did not feel any reduction in drag, so he un-feathered the left propeller. The airplane subsequently struck power lines and terrain during a forced landing. According to the copilot's written statement, the airplane was base leg to final leg for runway 5R, when the airplane started turning right and losing airspeed. The copilot asked for maximum power, and the crew chief moved the cockpit levers to the full forward position. The pilot then told the copilot that they were losing an engine, and asked which one. The copilot responded that he was holding right rudder. The airplane continued to lose altitude and airspeed, eventually striking power lines, trees, and terrain. The airplane broke up during the accident sequence, but did not catch fire. The pilot described his egress from the airplane, and the assistance rendered by a Navy corpsman and Marine swimmer who were lowered by rescue helicopter to the scene. These rescue personnel extracted the crew chief from the wreckage, and evacuated all occupants from the scene due to the forest fire ignited by the downed power lines. The fire subsequently consumed the airplane. WRECKAGE AND IMPACT INFORMATION Examination of photographs revealed that several feet of thick-gauge wire were wrapped around the left propeller hub, blades, and spinner. Both the leading and trailing edges of all three blades were nicked and gouged. The blades displayed similar pitch angles, with one blade bent aft at mid-span. The right propeller blades also displayed similar pitch angles, with one blade bent aft at mid-span. The photographs did not reveal any significant scratching or gouging of the blades. PERSONELL INFORMATION The pilot, age 70, held an airline transport pilot certificate with a rating for airplane multi-engine land. His most recent second-class medical certificate was issued on October 5, 2006. The pilot reported approximately 13,500 total hours of flight experience; of which, 11,000 hours were in mutli-engine airplanes, with 46 hours in the same make and model as the accident airplane. The copilot, age 76, held a commercial pilot certificate with ratings for airplane single engine land, multi-engine land, rotorcraft/helicopter, and instrument airplane and helicopter. His most recent second-class medical certificate was issued on January 8, 2007. The copilot reported approximately 6,200 total hours of flight experience; of which, 2,602 hours were in multi-engine airplane, with 8 hours in the same make and model as the accident airplane. AIRCRAFT INFORMATION The airplane was registered in the experimental category, and maintained under a Federal Aviation Administration (FAA) approved maintenance program. The airplane's most recent inspection was completed on March 20, 2007, at 8,962 aircraft hours. METEOROLOGICAL INFORMATION At 1417, the weather recorded at NKT included a scattered cloud layer at 2,000 feet, and a broken ceiling at 3,000 feet. The wind was from 050 degrees at 11 knots gusting to 19 knots. The temperature was 24 degrees Celsius, and the dew point was 18 degrees Celsius. The altimeter setting was 30.07 inches of mercury. ENGINE EXAMINATION On June 7, 2007, the right engine was examined under the supervision of the National Transportation Safety Board. The crankshaft was rotated by hand, and continuity was established through the powertrain and valvetrain to the accessories. Compression was confirmed at all cylinders using the thumb method. The dual magneto would not spark and was removed for further examination. Disassembly of the magneto revealed that the steel drive gear rotated, but the phenolic driven-gear shaft was frozen and would not rotate by hand. The phenolic gear was damaged and worn at the point where it mated with the driving gear. ADDITIONAL INFORMATION According to Naval Aviation Training and Operating Procedures (NATOPS) in NAVAIR 01-85SAA-1 (operator's manual), the memory items for ENGINE FAILURE IN FLIGHT were as follows: "1. RUDDER ASSIST ON 2. PROPS FULL INCREASE 3. THROTTLES AS REQUIRED 4. MIXTURES RICH 5. WHEELS UP 6. FLAPS AS REQUIRED Determine definitely which engine has failed before proceeding..." The manual outlined four methods by which the flight crew identifies the failed engine: "1. Heavy pressure on one rudder indicates the working engine. 2. Swerve of the aircraft will be toward the failed engine. 3. Failure of one set of RPM and MAP indicators to increase to higher power settings when steps 2 and 3 in Memory Items are performed. 4. Visual indicators of structural damage or engine fire." The manual then continues with the "Challenge and Reply Items" which stated, "Analyze these symptoms properly to ensure which engine has failed. Both pilots shall check the indications available, and the copilot shall make his recommendation to the pilot in command. When the determination is made by the pilot, proceed as follows using the challenge and reply method. 1. THROTTLE CLOSED 2. FEATHER BUTTON PUSH" The checklist continued with eleven total challenge and reply items. The operator's manual did not direct cabin crew to enter the cockpit and manipulate engine or flight controls during an emergency. The pilot reported that the airplane departed on the accident flight with 250 gallons of fuel, and that the fuel consumption rate in cruise flight was about 100 gallons per hour. The airplane's empty weight was 18,315 pounds, and its maximum allowable gross weight was 26,000 pounds. Interpolation of a single-engine rate of climb chart, at 24,000 pounds, with the propeller feathered, landing gear down, the flaps at 1/3 setting, and 120 knots airspeed, revealed a single engine rate of climb of about 100 feet per minute. In the same configuration with the propeller windmilling, the airplane's best single engine rate of climb was -440 feet per minute.
The flightcrew's failure to comply with the published emergency procedure following a loss of engine power on the right engine. Contributing to the accident was the failure of a magneto in the right engine.
Source: NTSB Aviation Accident Database
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