Pilot Debrief

PIPER AIRCRAFT INC PA-46-600TP near Olive Branch, MS — 2022-03-23

Final reportCEN22LA153
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Date
2022-03-23
Location
Olive Branch, MS, USA
Airport
OLV
Aircraft
PIPER AIRCRAFT INC PA-46-600TP
Registration
N627PR
Category
Airplane
Highest injury
None
Fatalities
0
Phase of flight
Landing

Probable cause

The airplane’s uncommanded hard right turn and loss of directional control during landing in crosswind conditions. Contributing to the accident were the dynamic instability of the nose landing gear and the crosswind conditions.

Contributing factors

Contributing to the accident were the dynamic instability of the nose landing gear and the crosswind conditions.

NTSB narrative

**This report was modified on July 22, 2026. Please see the public docket for this accident to view the original report.** The pilot was landing the airplane with a right quartering headwind, resulting in a right crosswind component of about 10 to 14 kts, which was less than but near the airplane’s maximum demonstrated crosswind component of 17 kts. The airplane touched down left of runway centerline. After touchdown, the pilot attempted to correct to the right toward the centerline with rudder inputs. As the airplane decelerated through about 68 kts and approached the runway centerline, the airplane entered a 45° hard right turn, and the pilot reported that he was unable to control the turn with left rudder input. The airplane departed the right side of the runway, about 1,330 ft from the threshold and about 570 ft after touchdown, and the nose landing gear (NLG) collapsed. The airplane sustained substantial damage to the engine mount. Postaccident examination of the runway surface revealed rubber transfer markings consistent with the NLG, right main landing gear (RMLG), and left main landing gear (LMLG). The NLG transfer mark began about 900 ft from the threshold and about 10 ft left of the centerline, with light intensity and its tread pattern evident, consistent with a rolling, non-skidding tire. The rolling tire marking continued until the right veering began, at which point it was of moderate intensity with tread pattern evident and transitioned to heavy intensity and no tread pattern, consistent with a skidding tire. A review of the airplane’s avionics data revealed that the RMLG touched down first, followed by the LMLG about 1 second later, consistent with a right crosswind landing. The NLG touched down about 1 to 2 seconds after the RMLG. Starting about 2 seconds after LMLG touchdown, the heading and track diverged, with the nose to the right of the track, until near the runway departure location, indicating that the airplane was in a skid. The maximum divergence occurred about 1 second before the runway excursion, when the heading was about 223° and the track was about 195°. At the same time, the lateral acceleration increased, also consistent with the airplane being in a left skid. The airplane departed the runway with the heading and track mostly aligned. Postaccident examination of the NLG assembly did not reveal anomalies that would have affected its operation or steering. However, damage precluded examination of the rake angle, NLG steering adjustments, and main landing gear (MLG) alignment. The rake angle of the NLG was designed to be 90° from the airplane longitudinal axis with a very tight tolerance of +0.5°/-0.0°, which equated to a 0.0° to 0.5° forward caster angle. For NLG to be directionally stable when rolling, they must have positive dynamic trail. However, because the M600 NLG was designed with zero caster angle and zero offset (and thus zero mechanical trail), positive dynamic trail was dependent on positive pneumatic trail. Pneumatic trail varies according to tire inflation pressure, tire speed, runway friction, and tire slip angle. In a 2008 customer information letter, the manufacturer cautioned operators that low tire pressure, excessive clearance between the steering arm and steering horn rollers, and low rudder cable tension could each result in the NLG pointing in a different direction than commanded by rudder pedal inputs, even if a pilot uses proper crosswind landing technique. In a 2020 service letter, the manufacturer directed operators to perform inspection and adjustment, as necessary, of NLG steering components at 100-hour intervals. The NTSB’s investigation compared the PA-46 series (including the M600) to airplane types with similar weight and power and found it to be unique in having NLG with zero caster angle and in requiring stringent NLG maintenance. When normalized for the number of airplanes produced, the PA-46 had the highest rate of veer events investigated by the NTSB among the compared airplane types. For this event, runway markings and simulation results indicated that the NLG was initially aligned with the runway upon touchdown, in accordance with proper crosswind landing technique for an airplane with steerable NLG, and then became fully deflected to the right within a few seconds. The investigation was unable to determine with certainty the source of the NLG steering inputs (that is, whether they were commanded by the pilot via the rudder pedals, the result of ground reaction forces on the tire, or a combination). However, the pilot’s description of the event, the design of the NLG that depended on variable pneumatic trail for directional stability, and the known behavior of the NLG when operated outside of tight maintenance tolerances all support an adverse airplane-pilot coupling event, in which a change in control forces or directional stability of the NLG steering system likely led to an unexpected response to control inputs and a loss of directional control. The manufacturer redesigned the lower NLG fork to move the axle 0.5 inches aft of the steering axis. This is equivalent to raking the NLG forward 5°, increasing directional stability. To the NTSB’s knowledge, no veer events have been reported with the new NLG design.

Analysis

Primary failure mode
Loss of control
First missed decision gate
Pilot could have maintained better control during landing approach.

NTSB coding

Evidence available

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  • 12 docket documents
View NTSB final reportView NTSB docket

Docket documents12

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