Ocean City, MD, USA
N849GS
VANS RV7
The pilot reported that, during takeoff, the airplane was about 500 ft above ground level when the engine lost partial power. The pilot verified that the throttle, mixture, and propeller were in the full forward position and chose to stay in the airport traffic pattern and land on the runway. The pilot noted that, during short final on approach, the airplane was "high and fast," but he still wanted to land on the runway to avoid landing in the water beyond the runway. The airplane landed hard, continued into the grass, and then nosed over and came to rest inverted, which resulted in substantial damage to the rudder. A postaccident engine examination was conducted. The propeller governor control arm was found disconnected from the propeller governor, and the control arm locking bolt was missing. In addition, the secondary control arm/spacer and spring were not located. No other anomalies were noted with the engine. The propeller governor control arm was reattached (without the missing parts), and fuel was plumbed into the engine; the engine started and ran smoothly. The propeller lever was operated with no anomalies noted. Then, the governor control arm was positioned in the low pitch, high rpm position to simulate takeoff conditions, and the governor control arm was disconnected. The engine was restarted and the throttle was advanced, but the engine rpm would not rise above 1,400 at maximum power, which was similar to the accident flight data downloaded from the engine information system on board the airplane. After the engine was shut down, examination of the governor control revealed that it had vibrated/turned to a high pitch, low rpm setting. It is likely that the absence of the control arm locking bolt that secured the propeller governor control arm to the propeller governor resulted in the control arm separating from the governor and then the governor control vibrating/rotating into a high pitch, low rpm setting, which resulted in a partial loss of engine power. The investigation could not determine if the bolt was not installed during the engine overhaul 28.5 flight hours before the accident or if the bolt backed out of the propeller control arm.
On July 19, 2019, about 1210 eastern daylight time, an experimental, amateur-built Vans RV-7A, N849GS, was substantially damaged after it experienced a partial loss of engine power during the initial climb after takeoff from Ocean City Municipal Airport (OXB), Ocean City, Maryland. The commercial pilot sustained minor injuries. The airplane was registered to and operated by the pilot as a Title 14 Code of Federal Regulations Part 91 flight. Visual meteorological conditions prevailed at the time of the accident and a visual flight rules flight plan was filed for the personal flight destined for Manassas Regional Airport (HEF), Manassas, Virginia. According to the pilot, he performed a preflight inspection of the airplane and an engine run-up with no anomalies noted. He taxied the airplane onto runway 20, applied full power, then, about 500 ft above ground level, the engine experienced a partial loss of power. The pilot verified that the throttle, mixture, and propeller were in the full forward position, and elected to stay in the airport traffic pattern and land on runway 14. He radioed on the UNICOM frequency and reported that he was landing on runway 14. On approach, the pilot noted that an airplane was entering runway 14 for departure. He radioed the pilot of the other airplane on the UNICOM frequency and asked him to abort the takeoff. The airplane exited the runway and the pilot continued his approach to runway 14. During short final on approach, the pilot noted that the airplane was "high and fast," but he still wanted to land on the runway in order to prevent landing in the water. He landed the airplane "hard," about 1,000 ft from the end of the runway and continued for about 150 ft into the grass. The airplane nosed over and came to rest inverted, which resulted in substantial damage to the rudder. An examination of the engine by a Federal Aviation Administration inspector revealed that compression was confirmed on all cylinders, fuel was noted in the fuel lines, and that there were no holes in the crankcase. According to FAA airworthiness records, the airplane was manufactured in 2004. It was equipped with a Superior Air Parts IO-360-B1A3, 180 hp engine. The most recent condition inspection was performed on August 8, 2018, at an airframe time of 431.0 hours, and the most recent overhaul of the engine was performed at that time. The time on the Hobbs meter when the airplane engine was examined was 459.5 hours. During an examination of the engine with an NTSB investigator, the engine cowling was removed to facilitate further engine examination. The governor control arm was found disconnected from the propeller governor and the control arm locking bolt was missing. In addition, the secondary control arm/spacer was not located, nor was the spring. Furthermore, the governor control arm pin that slid into the secondary control arm/spacer was not sheared and remained intact. No other anomalies were noted with the engine. The governor control arm was re-attached (without the missing parts), fuel was plumbed into the engine, the engine started and operated without anomalies. The engine throttle was advanced and the engine ran smoothly. The propeller lever was operated and the propeller moved from low pitch, high RPM, to high pitch, low RPM multiple times without anomaly. The propeller control was returned to low pitch, high RPM setting and the engine was shut down. Then, the governor control arm was positioned in the low pitch, high RPM position to simulate takeoff conditions. Furthermore, the governor control arm was disconnected since that was how it was initially found by investigators. The engine was restarted, the throttle was advanced, and the engine RPM would not rise above 1400 RPM at maximum power. After the engine was shutdown, the governor control had vibrated/turned and was observed in a high pitch, low RPM setting. A Grand Rapid Technologies Model 4000 Engine Information System was installed in the instrument panel. It was downloaded and the data was reviewed. The most recent flight data indicated that the RPM increased to about 2,600 RPM about 8 minutes and 15 seconds into the recording. Then about 450 ft in the air, and 8 minutes and 30 seconds into the recording, the tachometer decreased to about 1,500 RPM and maintained that RPM over the next one minute and 12 seconds until the engine power reduced to about 800 RPM and finally to 0 RPM.
The disconnection of the propeller governor control arm from the propeller governor due to a missing attachment bolt, which resulted in a partial loss of engine power during takeoff when the governor control vibrated to a high pitch, low rpm setting.
Source: NTSB Aviation Accident Database
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