Greenville, NC, USA
N49DD
CESSNA 421C
The accident pilot was preparing to fly the airplane back to its home base. When he taxied the airplane for departure the "Hydraulic Flow" light remained illuminated at a "higher than normal" engine rpm. He then taxied the airplane back to the ramp in order to have a mechanic investigate the cause for the light. The mechanic informed the pilot that it was "probably a sensor problem" and that the airplane should be safe to fly. The pilot then taxied back to runway 2 for departure. During the takeoff roll, at a speed of about 90 knots, the pilot heard a loud "bang." The airplane settled onto the runway, slid on the underside of the fuselage, and stopped on the right edge of the runway pavement. The damage was limited to the propeller tips, skin on the underside of the fuselage, and a penetration of the pressure vessel on the right side of the fuselage near the right cockpit seat. The airplane was loaded onto a trailer, and moved to another location on the airport for further examination. When the airplane was lifted from the trailer, the landing gear was manually extended and secured. Examination of the airplane by a Federal Aviation Administration inspector and a local mechanic revealed no preimpact deficiencies with the landing gear and the associated systems. The installation and functionality of the landing gear torque link safety switch was found to be in accordance with the manufacturer's guidance.
HISTORY OF FLIGHT On June 2, 2008, about 1705 eastern daylight time, a Cessna 421C, N49DD, was substantially damaged during an attempted takeoff from the Pitt-Greenville Airport (PGV), Greenville, North Carolina, when the landing gear retracted and the airplane settled onto the runway. The certificated airline transport pilot was not injured, and the passenger received minor injuries. Visual meteorological conditions prevailed, and no flight plan was filed for the flight destined for Wilmington International Airport (ILM), Wilmington, North Carolina. The executive/corporate flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. In a telephone interview with a Safety Board investigator, the pilot stated that as he taxied the airplane for departure, the "Hydraulic Flow" light remained illuminated at a "higher than normal" engine rpm. He taxied the airplane back to the ramp in order to have a mechanic investigate the reason for the discrepancy. The mechanic informed the pilot that it was "probably a sensor problem," and that the hydraulic reservoir was full. The pilot then restarted the left engine, which was the only engine that was shut down while the mechanic examined the hydraulic reservoir, and taxied back to the runway for departure. During the takeoff roll, when the airplane was at a speed of about 90 knots, the pilot heard a loud "bang." The nose of the airplane began to drop, and in response, the pilot applied back pressure to the control column. The right wing then dropped, followed by the left wing. The airplane settled onto the runway, slid on the underside of the fuselage, and stopped on the right edge of the runway pavement. INJURIES The pilot received no injuries from the accident. The passenger, who was seated in the right cockpit seat, received minor injuries to his right leg when he was struck by a propeller fragment. The fragment came from the propeller on the right engine. PERSONNEL INFORMATION The pilot, age 66, held an airline transport pilot certificate with ratings for airplane single and multi-engine land, and instrument airplane. His most recent second-class medical certificate was issued on July 12, 2007. The pilot reported 10,573 hours of total flight experience, and 2,713 hours in the accident airplane make and model. He also reported 10,400 hours of total flight experience as pilot in command. His most recent biennial flight review was conducted on October 28, 2007. AIRCRAFT INFORMATION According to Federal Aviation Administration (FAA) and maintenance records, the accident airplane was manufactured in 1976. The pressurized, eight-seat, multi-engine airplane was equipped with retractable tricycle landing gear, and had accrued 5566.3 hours time in service. The airplane was powered by two 375 horsepower Teledyne Continental Motors GTSIO520L engines. The left engine had 1,959.6 hours time in service, and 773 hours since major overhaul. The right engine had 3,827.5 hours time in service, and 773 hours since major overhaul. Each engine was equipped with a controllable pitch McCauley propeller. The maximum certificated gross weight of the airplane was 7,450 pounds, and the weight at the time of the accident was approximately 7,000 pounds. The most recent annual inspection was accomplished on October 3, 2007. At that time, the records indicated an airframe total time of 5,355.8 hours, and 195.8 hours on each of the left and right engines. The most recent maintenance records entries were for the day of the accident. These entries documented engine oil and filter changes for both engines, and replacement of the alternator on the right engine. METEOROLOGICAL INFORMATION The 1701 recorded weather at PGV included winds from 010 degrees at 4 knots, visibility 7 miles, clear skies, temperature 28 degrees Celsius (C), dew point 7 degrees C, and an altimeter setting of 29.96 inches of mercury. WRECKAGE AND IMPACT INFORMATION The airplane came to rest on the right edge of runway 2. The damage was limited to the propeller tips, skin on the underside of the fuselage, and a penetration of the pressure vessel. The pressure vessel puncture was on the right side of the fuselage near the right cockpit seat. Following an initial examination, the airplane was lifted from the runway surface, loaded onto a trailer, and taken to another location on the airport for further examination. When the airplane was lifted from the trailer, the landing gear was manually extended and secured. TESTS AND RESEARCH An FAA inspector and a mechanic inspected the airplane after the accident. The landing gear safety switch, which was installed on the left torque link, had 5/16 of an inch (approximately 0.31 inches) of clearance between it and the switch striker plate when the weight of the airplane was supported by the landing gear. The Cessna 421 Service Manual stated that the limits for this dimension were 0.30 to 0.35 inches. A test of the landing gear warning horn system was conducted. The inspector verified the functionality of the gear horn by applying a grounding wire to the center post of the horn. The airplane was configured with electrical power on, the gear handle in the "UP" position, and the weight of the airplane on the landing gear; the gear horn did not sound with any combination of throttle position or flap position. These results were not in accordance with the warning system design. The design specified that the gear horn should have produced an audible sound when either the flap lever was selected to 16 degrees or greater, or the throttle lever was reduced to a predetermined point specified in the maintenance manual. The condition of the circuit breaker for the warning system was not reported by the on scene personnel. Movement of the torque link assembly from a "weight on wheels" to a "weight off wheels" position resulted in a sound emanating from the safety switch when the relays activated. The landing gear actuators incorporated a mechanical latching mechanism to lock the gear in the "DOWN" position. The latching mechanism must be released hydraulically before the gear can retract. Hydraulic release of this latching mechanism requires that the cockpit landing gear lever is in the landing gear "UP" position, and the torque link safety switch must be in a "weight off wheels" position. The inspection did not reveal any preimpact deficiencies with the landing gear and the associated systems.
The malfunction and premature retraction of the landing gear for undetermined reasons.
Source: NTSB Aviation Accident Database
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