History of Flight
On May 4, 2013, at 1200 central daylight time, a Beech 58 twin-engine airplane, registration N44GC, sustained minor damage during a forced landing shortly after takeoff from Mena Intermountain Municipal Airport (MEZ) in Mena, Arkansas. The commercial pilot and the pilot-rated passenger were not injured. The airplane was operated by the passenger under 14 CFR Part 91. Visual meteorological conditions prevailed and no flight plan was filed for the intended flight to Bill and Hillary Clinton International Airport (LIT) in Little Rock, Arkansas.
The pilot reported that the airplane had just undergone interior refurbishment in Mena, and he was hired by the owner (the passenger) to fly it back to Little Rock. The owner was not current. Before departure, the pilot completed a preflight inspection and used the checklist to start both engines, which started immediately. After taxiing for about 10–15 minutes to runway 27, he performed an engine run-up on each engine using the checklist, which was normal. He then lined up on the runway, applied full power to both engines, and departed. Once airborne, he initiated a right turn. At about 1,200–1,400 feet, he brought the propeller levers back to 2,500 RPM and left power at 30 inches of manifold pressure (MP) on both engines. Almost immediately, he heard a faint, indistinguishable pop from the left engine, and then both engines simultaneously went from full power to idle. Unable to maintain altitude, he made an immediate turn back to runway 27. The pilot stated that the mixture controls were full forward throughout the flight, fuel tanks were three-quarters full, and the fuel selector was in the on position. The MP gauge read 30 inches and fuel flow was about 25 gallons per hour per side. He did not recall checking other gauges as he focused on landing. The airplane touched down gear-up on the grassy area just short of runway 27.
Aircraft and Pilot Information
The pilot held a commercial pilot certificate with multi-engine and instrument ratings, as well as a certified flight instructor certificate. His last FAA first-class medical was issued on April 4, 2013, with no waivers or limitations. He reported 1,381 total flight hours, including 250 hours in multi-engine airplanes and 32.6 hours in a Beech 58.
The airplane was a 1974 Beech 58 (serial number TH-453) with several modifications installed under FAA-approved Supplemental Type Certificates, including Continental Motors IO-550-C engines, 4-bladed Hartzell propellers, TurboGAMIjector fuel injectors, and a Merlyn Products turbo-normalizing system. An FAA-approved flight manual supplement for the Merlyn STC noted an operating limitation that manifold pressure must not exceed 30 inches, and a placard was required on the instrument panel; such a placard was found above the manifold and fuel pressure gauges. The last 100-hour inspection was completed in April 2013 at an aircraft total time of 7,785.2 hours. Both engines had approximately 974.2 hours at the time of the accident.
Wreckage and Engine Examination
On May 5, 2013, an FAA inspector examined the airplane and reported damage to propeller blades and landing gear doors, but no structural damage. Fuel samples were free of debris and water. On May 29–30, 2013, the NTSB conducted a detailed examination with representatives from the FAA, Continental Motors, Beechcraft, Hartzell, and Merlyn Products.
Airframe examination revealed separation of the main entrance step, left elevator counter-balance horn, and fuselage belly fairing. The left elevator was buckled mid-span, the nose landing gear doors were buckled, and there was a dent on the right wing leading edge. The fuel system showed no anomalies; fuel selector detents were distinct and flow was confirmed. Mid-wing fuel sight gauges indicated less than 60 gallons in the left and 55 gallons in the right, adequate for flight.
Both propellers were 4-bladed Hartzell units with blades bent aft mid-span, exhibiting leading edge to trailing edge scoring and span-wise scoring. The propellers were removed and replaced with 2-bladed McCauley propellers for testing. Crankshaft-propeller flange run-out and end-play checks showed no measurable results. Top spark plugs from both engines were removed; the left engine's No. 1 plug was black and carbon-fouled. All plugs produced normal spark on a test bench. Thumb compression checks via manual rotation established compression on each cylinder.
Engine Test Run
A calibrated pressure gauge was installed on the left engine to measure metered fuel pressure. The airplane was towed to a secure area for a dual engine run. Both engines started and warmed for about six minutes at idle. After a visual inspection for leaks (none found), magneto checks at 1,700 RPM showed about a 75 RPM drop, within limits. Propeller levers were exercised, and throttles were advanced. At full throttle (2,700 RPM), approximately 34 inches of manifold pressure was obtained, exceeding the 30-inch limitation; a pressure relief valve was supposed to limit MP to around 33 inches, and the reason for the higher reading was not determined. Throttle was reduced to achieve about 30 inches MP. The right engine was then run similarly. Subsequently, with the left boost pump in the high position and throttle retarded to about 1,400 RPM, engine roughness was detected. Leaning the mixture cleared the roughness, but returning to full rich caused roughness again. When the throttle was advanced, the engine quit. Both engines were secured. Post-test spark plug examination showed left plugs were darker than right, attributed to boost pump activation during testing. Except for the roughness event, both engines started and ran smoothly throughout the protocol. Black smoke was observed from the exhaust when throttles were retarded from high power. No mechanical deficiencies were noted that would have precluded normal operation.
Forced Landing Area
Impact marks at the forced landing site spanned about 280 yards. Early in the wreckage path, propeller slash marks indicated left propeller contact first, followed by right. Measured distances between blade strikes were used to calculate propeller RPM at various speeds: about 1,570 RPM at stall speed (83 knots), 1,700 RPM at landing speed (90 knots), and 1,890 RPM at best single-engine climb speed (100 knots). One runway threshold light was struck by the airplane, likely causing the right wing leading edge damage.
Data Recorder Analysis
The airplane was equipped with a Graphic Engine Monitor (GEM) 1200 data logging system that recorded the accident flight and subsequent test runs. The monitor was downloaded by the NTSB Recorder Laboratory. The GEM 1200 records exhaust gas temperature (EGT), cylinder head temperature (CHT), and turbocharger turbine inlet temperature (TIT) per engine; it does not record RPM, fuel flow, or MP. Data plotted on a graph indicated that the left engine lost power several seconds before the right engine, accompanied by a rise in EGT. According to the engine manufacturer, leaning the mixture could cause a smooth rise in EGT, but the pilot reported he did not move the mixture control during the short flight. CHT continued to climb after EGT declined on both engines, and EGT appeared to rise slightly again before data ended.
Probable Cause
The investigation did not determine a probable cause; no cause was stated in the source.