Victoria, TX, USA
N74CP
AERO COMMANDER 685
Two days before the accident, both engines lost power after takeoff. The pilot returned to the airport and landed the airplane uneventfully. Maintenance personnel were unable to determine the cause of the engines' power loss. Both engine wastegates were removed and bench tested, and they operated normally. Ground, high-speed taxi, and flight tests were conducted with no discrepancies noted. Earlier on the day of the accident, the airplane had been flown for an uneventful 45-minute flight. However, during takeoff for the accident flight, both engines lost power, and the pilot made a forced landing in a field. Disassembly of the left engine revealed that the idler pin was unsecured and that no nuts were present on either of the two bolt studs. The bolt studs were worn and stripped of threads near the base, consistent with being worn by the free movement of the idler pin. The engine casting where the idler pin was installed was fractured. The crankshaft, camshaft, starter drive, and starter adapter gear teeth were stripped, and metal fragments were noted in the oil screen and sump. The right engine was functionally tested and operated satisfactorily at all power settings. Based on the evidence found during the left engine examinations, it is likely that a catastrophic left engine failure occurred during the accident flight due to an unsecured idler pin.
HISTORY OF FLIGHTOn June 15, 2013, at 0947 central daylight time, the crew of an Aero Commander 685, N74CP, made a forced landing in a field after both engines lost power after takeoff from Victoria Regional Airport (KVCT), Victoria, Texas. The two pilots and passenger were seriously injured. The airplane was substantially damaged. The airplane was registered to Aero Investments, LLC, Cheyenne, Wyoming, but was reportedly sold to Ruth Trinh, Garden Grove, California, and was being operated under the provisions of 14 Code of Federal Regulations Part 91 as a business flight. Visual meteorological conditions prevailed, and no flight plan had been filed. The flight was originating at the time of the accident. The right seat pilot made the takeoff on runway 13L. Both engine parameters were 44.5 inches manifold pressure, 3,400 rpm, and 270 to 280 pph (pounds per hour) fuel flow. The airplane was rotated for liftoff at blue line. Immediately thereafter, manifold pressure dropped to 24 inches on the left engine and 28 inches on the right engine. Shortly thereafter, manifold pressure fell below 20 inches on both engines. Both engines maintained 3,400 RPM, but fuel flow dropped to 200 and 250 pph on the left and right engines, respectively. The pilot assumed control and made a forced landing in an open field east of the airport. The airplane landed hard, collapsing the nose landing gear, and slid 370 feet and pivoted more than 90 degrees to the right before coming to a stop. The tower controller said the airplane's takeoff roll was unusually long, approximately 6,000 feet. When asked about the long takeoff distance, the pilot said they intentionally kept the aircraft on the ground to achieve a faster than normal takeoff speed of 110 KIAS. He stated that normal takeoff distance is about 1,900 feet, and that they used 2,500 to 3,500 feet of runway. On June 13, two days prior to the accident, as the airplane was taking off from Houston Intercontinental Airport (KIAH), both engines lost power. In that case, manifold pressure dropped to 20 and 22 inches on the left and right engines, respectively (normal takeoff manifold pressure is 44 inches). Fuel flow was 230 and 200 pph, respectively (normal takeoff fuel flow is between 270 and 280 pph). Ground witnesses saw white smoke coming from one of the engines. The pilot was able to return to KIAH for landing. Maintenance personnel were unable to determine the cause of the power loss. According to the maintenance work order, dated June 13, 2013, both engine wastegates were removed and bench tested and operated normally. Ground, high speed taxi, and flight tests were made no discrepancies noted. On June 15, 2013, the day of the accident, the airplane departed KIAH for an uneventful 45-minute flight to KVCT for the purpose of familiarizing the copilot --- the new owner's pilot --- with the airplane. The new owner was aboard as a passenger. After the accident, the fuel vendor at KIAH tested their fuel supply and found no contamination. Fuel drained from N74CP at the accident site appeared clean and uncontaminated. PERSONNEL INFORMATIONThe pilot-in-command, age 58, held an airline transport pilot certificate with airplane single and multi-engine land ratings. He also held a first class airman medical certificate, dated April 17, 2012, with no restrictions or limitations. When the pilot applied for this medical certificate, he estimated his flight time to be 8,860 hours and 28 hours in the Aero Commander 685. His last flight review was on July 7, 2012. The second pilot, age 30, who was receiving familiarization training and a checkout in the airplane, held a commercial pilot certificate with airplane single/multiengine land and instrument ratings. He also held a flight instructor certificate with an airplane single-engine land rating. He held a first class airman medical certificate, dated January 9, 2013, with a restriction that he wear corrective lenses. When he applied for this medical certificate, he estimated his flight time to be 2,291 hours and 1 hour in the Aero Commander 685. His last flight review was on March 29, 2013. AIRCRAFT INFORMATIONN74CP (serial number 12061), a model 685, was manufactured by Aero Commander in 1974. It was powered by two Continental GTSIO-520-K1B engines, rated at 435 horsepower each, driving two Hartzell HC H3YN-2UF propellers (hub DV13, left; DV14, right). According to the maintenance records, the last airframe annual inspection was accomplished on June 5, 2013, when the Hobbs meter indicated 952.8 hours and the airframe had accumulated 3,484.2 total hours. The left engine (serial number 605054) was given a 100-hour inspection on June 5, 2013, at a Hobbs meter time of 952.8 hours. At that time, the engine had accrued 1,795.5 hours. The engine received a major overhaul on March 13, 2009, after it had acquired 1,681.6 hours. At that time, the Hobbs meter read 838.5 hours. At the time of the most recent 100-hour inspection, the engine had accrued 114.3 hours since major overhaul. The left propeller was overhauled on July 1, 2011, and installed on N74CP on April 17, 2012, at an airframe total time of 3,466.8 hours, and a Hobbs meter reading of 935.4 hours. The propeller had acquired 17.4 hours since overhaul. The right engine (serial number 605138) was also given a 100-hour inspection on June 5, 2013, at a Hobbs meter time of 952.4 hours. At that time, the engine had accrued 1,795.5 hours. The engine received a major overhaul on July 14, 1999, after it had acquired 725.6 hours. The Hobbs meter reading was not given. At the time of the most recent 100-hour inspection, the engine had accrued 1,069.9 hours since major overhaul. The right propeller was overhauled on July 1, 2011, and installed on N74CP on April 17, 2012, at an airframe total time of 3,466.8 hours, and a Hobbs meter reading of 935.4 hours. The propeller had acquired 17.4 hours since overhaul. METEOROLOGICAL INFORMATIONThe following METAR (METeorological Aviation Routine, or aviation routine weather report) was recorded by the Victoria Regional airport (KVCT) ASOS (Automated Surface Observing System) at 0951: Wind, 180 degrees at 9 knots; visibility, 10 statute miles; sky condition, few clouds at 2,200 feet; temperature, 30 degrees C. (Celsius); dew point, 24 degrees C.; altimeter setting, 29.99 inches of mercury. AIRPORT INFORMATIONN74CP (serial number 12061), a model 685, was manufactured by Aero Commander in 1974. It was powered by two Continental GTSIO-520-K1B engines, rated at 435 horsepower each, driving two Hartzell HC H3YN-2UF propellers (hub DV13, left; DV14, right). According to the maintenance records, the last airframe annual inspection was accomplished on June 5, 2013, when the Hobbs meter indicated 952.8 hours and the airframe had accumulated 3,484.2 total hours. The left engine (serial number 605054) was given a 100-hour inspection on June 5, 2013, at a Hobbs meter time of 952.8 hours. At that time, the engine had accrued 1,795.5 hours. The engine received a major overhaul on March 13, 2009, after it had acquired 1,681.6 hours. At that time, the Hobbs meter read 838.5 hours. At the time of the most recent 100-hour inspection, the engine had accrued 114.3 hours since major overhaul. The left propeller was overhauled on July 1, 2011, and installed on N74CP on April 17, 2012, at an airframe total time of 3,466.8 hours, and a Hobbs meter reading of 935.4 hours. The propeller had acquired 17.4 hours since overhaul. The right engine (serial number 605138) was also given a 100-hour inspection on June 5, 2013, at a Hobbs meter time of 952.4 hours. At that time, the engine had accrued 1,795.5 hours. The engine received a major overhaul on July 14, 1999, after it had acquired 725.6 hours. The Hobbs meter reading was not given. At the time of the most recent 100-hour inspection, the engine had accrued 1,069.9 hours since major overhaul. The right propeller was overhauled on July 1, 2011, and installed on N74CP on April 17, 2012, at an airframe total time of 3,466.8 hours, and a Hobbs meter reading of 935.4 hours. The propeller had acquired 17.4 hours since overhaul. WRECKAGE AND IMPACT INFORMATIONBoth main landing gears were twisted and the nose gear had collapsed, buckling, the mounting structures. TESTS AND RESEARCHBoth engines were examined at Air Salvage of Dallas (Texas) on June 27 and 28, 2013. It appeared the left engine accessory gear drive had failed catastrophically, rendering the engine inoperative. Both engines were boxed and shipped to Continental Motors for further examination. On November 11, 2013, the left engine was disassembled and inspected. The engine exhibited minimal damage but during disassembly, several crankshaft and camshaft gear teeth were found to be missing. Although the oil pump was undamaged, metal fragments were noted in the oil screen and sump. The starter drive and starter adapter shaft teeth were stripped. The idler pin was found unsecured, and there were no nuts on either of the two bolt studs. They were never found. The bolt studs were worn and stripped of threads near the base, consistent with the free movement of the idler pin. Several of the idler gear teeth were scored. The engine casting where the idler pin was installed was fractured. Part of the casting was found in the oil sump. On November 14, 2013, the right engine was examined. The engine baffles were removed to facilitate functional testing. The engine rotated smoothly when the propeller flange was turned by hand. The engine was re-crated and stored in a secure area. On November 21, 2013, the engine was functionally tested and it operated satisfactory at all power settings. Manifold pressure was about 2 inches low. The two JPI Engine Data Monitors (EDM-800) were removed from the airplane and sent to NTSB's Vehicle Recorder Division for download. According to the Specialist's report, at time marker 9:40:13 CDT, the exhaust gas temperature (EGT), cylinder head temperature (CHT), fuel flow, and turbine inlet temperature (TIT) parameters drop to values consistent with engine idle. At about 09:50:23 CDT, the left engine EGT's begin to drop and the other left engine parameters begin to follow.
Maintenance personnel's failure to secure the left engine idler pin during overhaul, which resulted in a catastrophic engine failure and subsequent forced landing.
Source: NTSB Aviation Accident Database
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