What Happened
On February 16, 2021, a Velocity Vtwin experimental twin-engine pusher, registered N13VT, departed Southern Wisconsin Regional Airport (JVL) in Janesville, Wisconsin at approximately 0912 central standard time and never made it back. Both pilots sustained fatal injuries. The airplane came to rest inverted in a 3-foot-deep tributary of the Rock River, about 1 mile south of the runway, with both wings, both canards, and the fuselage substantially damaged.
The flight had started earlier that morning in Appleton, Wisconsin. The two pilots had departed Appleton International Airport (ATW) around 0634 and landed at JVL about 0715 to top off with fuel. Records from the fixed base operator at JVL showed the airplane took on 53.5 gallons of 100LL. The purpose of the trip was a ferry flight south to Sebastian, Florida, where maintenance was to be performed on the landing gear system. Because the landing gear system was the problem, the FAA had issued a Special Flight Permit with a specific limitation written into it: gear to remain down during flight. The permit also authorized a co-pilot, even though the airplane only required a single crewmember to operate. The previous flight leg from Appleton to Janesville had already been completed. This was leg two.
Shortly after liftoff from JVL, the right seat pilot contacted the tower and said they wanted to circle back and land runway 32 to work through some engine issues. The controller acknowledged, asked the pilot to report turning onto final for runway 32, and asked whether any assistance was needed. The pilot replied, “no sir, we should be fine.” Those were the last recorded words from N13VT. Data recovered from the Garmin G3X avionics aboard the airplane filled in what happened next. Around 0912:15, right engine RPM dropped from roughly 2,600 to approximately 2,100. At the same time, airspeed began climbing, eventually reaching a peak of about 156 knots, and the airplane climbed to around 2,850 feet. Then, around 0914:00, the right engine RPM began dropping again. By 0914:10, it had reached zero. The airplane entered a descent that continued until the data ended.
The tower controller on duty watched the airplane south of the airport maneuvering what looked like a modified base-to-final turn. He saw it begin circling left. About halfway through that turn, the bank angle increased sharply, and the airplane disappeared behind the tree line. It had struck trees and gone inverted into the river. Both propellers were found in the feathered position when the wreckage was pulled from the water. The throttle, propeller, and mixture controls for the left engine were found pushed further aft than the right engine controls, which is consistent with someone having intentionally shut the left engine down.
Investigation Findings
The NTSB’s vehicle performance study, built from the two Garmin G3X displays recovered in the wreckage along with ADS-B data, painted a clear picture of the sequence. The right engine data came from the MFD. The PFD, which would have captured left engine data, yielded only GPS information. That absence of left engine data turned out to be significant. What investigators found in the wiring told a story all on its own. The left engine oil pressure sending unit wiring harness was damaged in a way that was not consistent with impact. The red wire had separated into two pieces. The insulation on the green and black wires showed visible cuts. When investigators tested the sending unit using a surrogate wiring harness on an exemplar Velocity Vtwin, the sensor worked fine. The damaged wiring, not the sensor itself, was the problem. And according to Velocity, if the Garmin G3X failed to receive data from the sending unit, a red X would appear over the oil pressure indication on the display. So the pilots were almost certainly looking at a red X on the left engine oil pressure gauge, not because the left engine had a problem, but because the wiring harness had pre-existing damage that caused a false indication.
That false indication appears to have driven the decision to shut down the left engine. With the left engine secured and the airplane now flying on the right engine alone, the pilots needed to return to the runway. As they accelerated, indicated airspeed climbed to approximately 156 knots. The Velocity Vtwin’s maximum landing gear extended speed, VLE, is 140 knots calibrated airspeed. The maximum gear operation speed, VLO, is 120 KCAS. At 156 knots, the airplane was 16 knots past VLE with the gear hanging in the breeze. The right main landing gear door separated from the airplane. It was never recovered. One propeller blade from the right engine was found at the base of a tree that was the initial impact point, with damage to the metal leading edge consistent with screw or bolt threads. The other two right engine propeller blades were never found. All three had separated approximately 18 inches outboard from the hub. The damage to that one recovered blade told investigators exactly what had happened: the gear door came off and hit the propeller. That impact destroyed the right engine’s ability to produce thrust. Now both engines were gone.
Data from the previous flight leg, Appleton to Janesville, showed the airplane had been flown well above VLE on that leg as well, despite the ferry permit restriction. Fuel flow data from that leg was consistent with 75% cruise power. Investigators noted that repeated exceedances of VLE on both flights may have weakened the right landing gear door attachment points before the door finally departed. Additionally, with the left engine shut down and the airplane in asymmetric flight, the sideslip angle required to maintain coordinated flight would have placed higher-than-normal aerodynamic loads on the door. Toxicology results from the left seat pilot identified bupropion at 741 ng/ml, its metabolite hydroxybuproprion, and amphetamine at 58 ng/ml. Bupropion carries warnings about seizure risk and impairment of mental and physical ability required for hazardous tasks. Amphetamine is a Schedule II controlled substance. Whether those substances or underlying conditions played a role in the accident could not be determined. The investigators could not determine which pilot was flying at the time of impact, though the right seat pilot, who had received type-specific training in the Velocity Vtwin in September 2020, was likely acting as pilot-in-command.
NTSB Probable Cause
The exceedance of the maximum airspeed for flight with the landing gear extended, which resulted in a separation of the right main landing gear door that subsequently impacted the right propeller and resulted in a total loss of right engine power. Contributing to the accident was the damaged wiring harness of the left engine oil pressure sending unit, which gave a false indication of an engine malfunction that resulted in the precautionary shutdown of the left engine.
Safety Lessons
Three things had to go wrong in sequence for this accident to happen. Any one of them, caught earlier or handled differently, might have broken the chain.
- A red X is not an engine failure. The Garmin G3X displays a red X when it loses communication with a sensor. That is not the same thing as a failed engine. Before pulling a throttle, retarding a mixture, or feathering a propeller, pilots need to cross-check every available instrument. Oil temperature, fuel flow, EGT, RPM, and engine sounds should all be consistent with the indication before treating it as real. On the Velocity Vtwin, the left engine had no mechanical anomaly whatsoever. The wiring harness had pre-existing damage that the crew either did not know about or did not investigate before departure.
- Permit limitations are not suggestions. The special flight permit said gear stays down. Both legs of this ferry flight were flown well above VLE. The Appleton-to-Janesville leg showed fuel flows consistent with 75% cruise power and airspeeds above the 140-knot gear-extended limit. Every knot above VLE added aerodynamic load to a landing gear door that was never designed for those conditions, and investigators believe that repeated overloading weakened the attachment points before the door finally let go on the accident leg. The permit limit existed precisely because the landing gear system was already known to have problems. Flying above VLE on a flight specifically conducted to address a landing gear problem compounded an already-degraded system.
- On a twin, airspeed management after an engine loss determines whether you have options. With the left engine shut down, the pilots were flying a single-engine approach profile in a pusher twin with the landing gear extended. In that configuration, airspeed control is everything. Accelerating past VLE while single-engine, with a structurally stressed gear door, removed the last good engine from the equation. The performance study showed the airplane did not have sufficient energy to glide back to the runway from where the right engine quit. Slower, more deliberate airspeed management after the left engine shutdown would have kept the right engine intact and kept options open.
Frequently Asked Questions
Q: What is VLE and why does it matter on a ferry flight with gear down?
A: VLE is the maximum airspeed at which an airplane may be flown with the landing gear extended. On the Velocity Vtwin, that speed is 140 knots calibrated airspeed. Above VLE, aerodynamic loads on the gear doors, doors that were designed for slow-speed extension and retraction, exceed what the structure is rated to handle. On a ferry flight specifically mandated to keep the gear down, staying below VLE was not a performance suggestion — it was the structural limit protecting the airplane’s gear doors from departing in flight.
Q: Can a damaged wiring harness cause a false oil pressure warning on a Garmin G3X?
A: Yes. According to Velocity, if the G3X loses communication with the oil pressure sending unit, it displays a red X over the oil pressure indication rather than a numeric reading. A broken or shorted wiring harness can interrupt that signal without any actual change in oil pressure. In this accident, the left engine oil pressure sending unit wiring harness had damage with visible cuts that were not consistent with impact damage, meaning the damage existed before the accident. The sensor itself tested fine. The airplane’s left engine had no mechanical anomaly at all.
Q: What happened to the right propeller blades on N13VT?
A: All three blades from the right engine propeller separated approximately 18 inches outboard of the hub. Only one was recovered, found at the base of a tree that was the airplane’s initial impact point. That recovered blade had damage to its metal leading edge consistent with screw or bolt threads, which investigators determined was caused by impact from the right main landing gear door after it separated from the airplane. The prop strike destroyed the right engine’s ability to produce power.
Q: Why did the NTSB say the previous flight leg contributed to the accident?
A: Data recovered from the Garmin G3X showed that during the Appleton-to-Janesville leg, the airplane was flown well above VLE, with fuel flow consistent with 75% cruise power. Every exceedance of VLE places higher-than-rated loads on the landing gear door attachment points. Investigators concluded that repeated overloading on both the inbound leg and the accident leg may have weakened the door attachments before the door finally separated. Additionally, the sideslip angle required to fly coordinated with the left engine shut down would have added further asymmetric load to the already-stressed right gear door.
Q: What is a Special Flight Permit and what were the restrictions on this flight?
A: A Special Flight Permit, sometimes called a ferry permit, allows an aircraft that does not currently meet airworthiness requirements to be flown for a specific purpose — usually to reach a maintenance facility. The FAA issues the permit with specific operating limitations. In this case, the standard limitation restricted occupancy to the pilot, essential crew, and personal baggage. The FAA added a specific limitation requiring the gear to remain down during flight and authorized a co-pilot. Both limitations were there because the landing gear system was the known problem requiring maintenance. The data showed the crew did not comply with the airspeed restrictions those limitations implied.
