West Pittsfield, ME, USA
N932MC
MORMILE FRANCIS W AVENTURA II
The airline transport pilot departed in his amateur-built airplane and planned to stay in the airport traffic pattern to conduct a functional test of the retractable landing gear. He stated that, as he was turning the airplane left to the final leg of the airport traffic pattern, he noticed that the controls were "very stiff" when he tried to roll the airplane level and needed two hands to move the control wheel. The airplane then began to descend. The pilot was unable to level the airplane, and during the continued descent, it collided with trees. After the accident, two witnesses told the pilot that the engine had stopped producing power before the airplane impacted the trees; however, the pilot said he was unaware that the engine had lost power. Postaccident examination of the flight controls revealed no evidence of any preimpact mechanical malfunctions or failures that would have precluded normal operation. Postaccident examination of the engine revealed that the engine exhaust was positioned too close to fuel lines, which did not have heat shielding protection, and that a mandatory fuel return line was not installed, both of which could result in vapor lock to the engine. However, when the engine was test-run, it ran continuously for several minutes without hesitation. Given the successful engine test-run, it is unlikely that vapor lock caused the loss of engine power. Despite the noted deficiencies with the engine's installation, no preimpact mechanical functions or failures of the engine's powertrain were found that would have precluded normal operation. Examination of the airplane also revealed that the carburetor heat was not functional. Given that the atmospheric conditions at the time of the accident were conducive to carburetor icing at glide engine power settings, the carburetor likely accumulated ice. If the engine lost total power due to the accumulation of carburetor ice and the pilot inadvertently allowed the airplane to slow, then the effectiveness of the airplane's flight controls would have been degraded and likely would have resulted in the loss of airplane control, as reported by the pilot. Therefore, it is likely that the carburetor accumulated ice because the carburetor heat was not functioning, which led to the total loss of engine power.
HISTORY OF FLIGHTOn July 9, 2016, about 1453 eastern daylight time, an experimental amateur-built Aventura II airplane, N932MC, was substantially damaged when it impacted terrain while on approach to Grignons Private Landing Area (ME62) in West Pittsfield, Maine. The airline transport pilot sustained minor injuries. The airplane was registered to and operated by the pilot. Visual meteorological conditions prevailed for the personal flight conducted under the provisions of 14 Code of Federal Regulations Part 91. No flight plan was filed for the flight that departed ME62 about 1450. The pilot stated that the purpose of the flight was to perform a functional test of the retractable landing gear. He said he started the engine and taxied for about 10 minutes before he departed. The takeoff was normal and the pilot made a left turn to stay in the airport traffic pattern and climbed to an altitude of about 200 ft. The pilot said that when he was making the turn toward the final approach leg of the traffic pattern, he noticed the controls were very stiff when he tried to roll level. He needed two hands to move the control wheel. The pilot also noticed that he was descending and was unable to avoid trees off the side of the runway. The airplane struck the trees and impacted the ground in a nose-down attitude. Two witnesses told the pilot that the engine stopped producing power prior to the airplane impacting the trees. The pilot said he was wearing a full-size helmet and was unaware that the engine had lost power and was focused on trying to level the airplane. PERSONNEL INFORMATIONThe pilot held an airline transport pilot certificate with ratings for airplane single and multiengine land and single-engine sea. In addition, he held ratings for balloon and rotorcraft-helicopter and an instrument rating for airplane and rotorcraft-helicopter. The pilot also held a flight instructor certificate with ratings for airplane single and multiengine. He reported a total of 6,763 total flight hours, of which, 44 hours were in the accident airplane. His last Federal Aviation Administration (FAA) first class medical was issued on November 20, 2015. AIRCRAFT INFORMATIONThe airplane was originally built in 2008 and then sold to the pilot in January 2015, when it was still in Phase I testing for an FAA special, experimental airworthiness certificate. The pilot made an entry in the aircraft maintenance logbook on June 24, 2016, that Phase I testing was completed and had moved into Phase II testing. A review of the engine maintenance logbook revealed the Rotax 912ULS engine was installed new on the airplane on April 8, 2008. The pilot reported the engine had accrued a total of about 35 hours at the time of the accident. The airframe had accrued about 44 hours total time. METEOROLOGICAL INFORMATIONWeather reported at Bangor International Airport (BGR), Bangor, Maine, about 23 miles west of the accident site, at 1453, was wind 130 at 5 knots, visibility 10 miles, overcast clouds at 1800 ft, temperature 18° C, dewpoint 12° C, and a barometric pressure setting 29.96 inches Hg. AIRPORT INFORMATIONThe airplane was originally built in 2008 and then sold to the pilot in January 2015, when it was still in Phase I testing for an FAA special, experimental airworthiness certificate. The pilot made an entry in the aircraft maintenance logbook on June 24, 2016, that Phase I testing was completed and had moved into Phase II testing. A review of the engine maintenance logbook revealed the Rotax 912ULS engine was installed new on the airplane on April 8, 2008. The pilot reported the engine had accrued a total of about 35 hours at the time of the accident. The airframe had accrued about 44 hours total time. WRECKAGE AND IMPACT INFORMATIONPostaccident examination of the airplane revealed that it sustained substantial damage to the fuselage and both wings. Flight control continuity was confirmed from the control surfaces to the cockpit controls. The engine remained attached to the airframe and all three propeller blades remained attached to the propeller hub. The engine and blades sustained minimal impact damage. The airplane was not equipped electronic device to record engine performance. A postaccident examination of the engine revealed the fuel system consisted of a fuel pump that was equipped with two carburetors, both of which were removed and disassembled. Each float bowl was empty of fuel and a small amount of corrosion was noted underneath the floats in each bowl. Both carburetors were then reinstalled back on the engine. Examination of the fuel lines revealed that a fuel pressure indicator was installed but it was not connected electrically. The gascolator bowl was removed and examined. The bowl was about half full of fuel that was absent of debris and water. The oil pump, oil filter, oil cooler and the oil tank appeared undamaged. That oil tank was filled with the proper amount of oil needed to safely operate the engine. The exhaust system was an after-market installation (non-Rotax). The exhaust, which included four exhaust pipes and a muffler, were mounted above the engine near temperature sensitive components and fuel lines. No heat shielding was installed to protect these components from radiant heat. According to Rotax's Engine Installation manual (EIM), "To avoid vapor lock keep the temperature of the fuel lines, float chamber and related devices below 113F (45C)." The electronic ignition modules were also found near the exhaust and have a maximum temperature of 176° F. The induction system, which consisted of an optional AirBox, air filter, and carburetor heat, revealed the linkage that allowed the pilot to switch from filtered air to carburetor heat was not connected. The lever was positioned so induction air was being pulled from the carburetor heat side of the AirBox (non-filtered air). The carburetor heat was not operational. The air filter was grey in color and was not coated with the protective "red" oil that kept dirt particles from entering the engine. The spark plugs were removed and no anomalies were noted. The engine's crankshaft was rotated and continuity and compression were established on each cylinder via manual rotation of the propeller. The engine was prepped to be test run, which involved using a car battery with battery cables to boost the airplane's battery. After several attempts, the engine started and ran at idle for several minutes before the throttle was advanced to a higher power setting. The engine ran continuously at this higher setting for several minutes without hesitation. No mechanical deficiencies were noted that would have precluded normal operation of the engine. ADDITIONAL INFORMATIONA review of the engine maintenance logbooks revealed the fuel pump was installed new in 2015 per Rotax Service Bulletin SB-912-063: Replacement of fuel pumps for ROTAX Engine type 912 (series). The SB was issued in March 2013 and the replacement of the pump was only "Recommended". According to a representative of Rotax, when the new fuel pump was installed, a mandatory fuel return line should have been installed to prevent vapor lock. The fuel return line was made mandatory via an amendment to the Rotax 912 Series Engine Installation Manual (EIM) on August 1, 2012. No other notifications were issued. However, further review of SB 912-063 revealed there was no guidance or reference that the return fuel line was mandatory. It only stated that the person installing the new fuel pump should use the Illustrated Parts Catalog and Heavy Maintenance Manual (HMM) for guidance. Neither of those manuals stated the fuel return line was mandatory. A review of the FAA's Carburetor Icing Probability Chart revealed that atmospheric conditions were conducive to serious icing at glide power.
The pilot's failure to maintain airplane control after a total loss of engine power due to carburetor icing, which accumulated because the carburetor heat was not functioning.
Source: NTSB Aviation Accident Database
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