N916TCVelocity VELOCITY TXL · 2013

On July 23, 2016, about 0930 eastern daylight time, an experimental amateur-built Velocity TXL, N916TC, was substantially damaged during a forced landing after takeoff from Sebastian Municipal Airport (X26), Sebastian, Florida. The commercial pilot and passenger were not injured. The personal flight was conducted under the provisions of 14 Code of Federal Regulations Part 91. Visual meteorological conditions prevailed, and no flight plan was filed for the flight, which originated from X26, about 0925.

According to the pilot, he noted that the engine did not start right away on the first attempt. He then primed the engine and it started up immediately. Once the engine was started he then noted that the multi-function display (MFD) did not illuminate. As he began to taxi to the runway the MFD began to operate correctly. The pilot checked all the instruments prior to takeoff and all indications were in the green. During the takeoff roll, he noted that he used up more of the runway than usual. Once the airplane rotated, he noticed that it was not climbing and then the engine lost total power. He did not have time to attempt a restart of the engine and performed a forced landing to a field.

A cursory postaccident examination of the airplane by a Federal Aviation Administration (FAA) inspector revealed the left canard was separated from the fuselage. The engine remained attached to the airframe and displayed impact damage. Engine control cable continuity was established by moving the engine controls in the cockpit and observing the controls on the engine. The cylinders were inspected using a lighted borescope; all cylinders, piston faces, and valve heads displayed normal operating and combustion signatures. The crankshaft was rotated by hand and it was noted that all cylinders displayed thumb compression and suction.

The fuel pump remained attached to its installation point and was undamaged. All of the fuel lines were secure and the mixture control arm remained secure to the control shaft. The throttle and fuel metering assembly remained attached to its installation point and was undamaged. The throttle control arm remained secure to the shaft and operated normally. The fuel manifold valve remained attached to its installation point and was undamaged; there were no signs of fuel leaks around the manifold valve. All the nozzles remained installed in their cylinders and were undamaged.

Both magnetos remained attached to their installation points and were undamaged. The ignition harness remained secured to both magnetos and to all the spark plugs. The spark plugs were removed and visually inspected, all the spark plugs displayed normal wear signatures. Several of the spark plugs displayed soot on the electrodes and insulator. It was determined that an engine test run could be performed. A new rocker box cover was installed and made a temporary repair to the No. 2 exhaust riser to facilitate the test run. During the test run the engine would run normally until the manifold pressure went above 36"; above 36" of manifold pressure, the engine would stumble then lose power. It was noted that the TSIO-550-C is only certified for a manifold pressure of 35.5", but according to a representative from the airframe kit manufacturer, it is normal for the engine to over-boost in this application and it is the pilot's responsibility to throttle limit the manifold pressure.

Another test run was performed and the engine started normally without hesitation or stumbling. The engine was operated at approximately 1,000 RPM for several minutes to allow the engine to warm up to operating temperature. After the engine had warmed up to operating temperatures the engine was ran at 2,600 RPM with approximately 35.5" of manifold pressure. The engine operated normally at that power setting; however, it was noted that the fuel flow was significantly higher than the specified fuel flow for a TSIO-550-C engine. The observed fuel flow was approximately 43 gallons per hour, the maximum specified fuel flow indicated in the TSIO-550-C maintenance and overhaul manual is 224 lbs. per hour (approximately 37.3 gallons per hour). The engine was manually leaned using the mixture control to approximately 38 gallons per hour. The throttle was then pushed full forward to simulate a pilot not throttle limiting the manifold pressure; the engine ran normally. The mixture was then pushed full forward and the engine immediately began to run rough and witnesses outside the aircraft stated black smoke was coming out of the tailpipe. The fuel flow was noted to go above 50 gallons per hour followed by a complete loss of engine power.

After the engine lost power, the fuel pump high end adjustment was adjusted approximately 2 turns clockwise to lean the mixture at full power. The engine was started and was ran at 1,500 RPM for a brief period to stabilize. The engine was then accelerated to 2,600 RPM and 35.6 manifold pressure; it was noted that the fuel flow indicated 34.2 gallons per hour. The engine ran normally and there was no roughness noted. The throttle was then pushed full forward to simulate a pilot not throttle limited the manifold pressure; the manifold pressure reached 37.7" and the fuel flow was noted to be 39.7 gallons per hour. There was no roughness noted and the engine operated normally.

After the engine test run the NTSB requested for the fuel pump to be shipped to the Continental Motors Inc. in Mobile, Alabama for testing under FAA oversite. During the testing it was noted the fuel pump was previously tested on the engine and during the first test it was discovered that the aneroid adjustment was set for too rich of a mixture. After the aneroid adjustment was readjusted for a leaner mixture the fuel pump operated normally on the test bench without any anomalies.

Review of logbook excerpts revealed the airplane's most recent condition inspection was completed on April 16, 2016, at an airframe time of 161.1 hours. Further review of the work order revealed that on March 7, 2016 the fuel pump was removed, disassemble and inspected. During the inspection the fuel pump aneroids were found inoperative and were reassembled and reinstalled on March 28th.