Leesburg, VA, USA
N282ST
PIPER PA46
The pilot reported that, after touchdown, while rolling straight down the runway, the airplane “went careening to the left.” He stated that the right brake locked, and the right main landing gear (MLG) tire “blew” as the airplane skidded. The pilot applied rudder and brake inputs to correct the deviation and was able to straighten the airplane’s path; however, the airplane exited the left side of the runway and came to rest in the grass. The calculated crosswind component at the time of landing was 7 kts with gusts to 12 kts. Examination of the runway revealed distinct tire marks from the nose landing gear (NLG) and both MLG extending from the touchdown point on the runway to where the airplane exited the left side of the runway. The NLG tire mark was a dark, wide line with no evident tread pattern, consistent with the airplane skidding from the touchdown point to the runway departure point. The left MLG tire marks displayed an evident tread pattern consistent with tires rolling under the application of brakes for the entire length. The right MLG tire marks had an evident tread pattern, consistent the tires rolling while braking was being applied, that then changed to a dark wide mark consistent with a skidding tire. The rubber transfer marks then changed to a light mark, likely as a result of the right MLG tire deflating due to wear through the tread. Examination of the NLG revealed that the tire’s right sidewall exhibited crosswise scuffing and the NLG fork was bent left about 10° left. A review of avionics data revealed that the airplane experienced an initial slight lateral acceleration to the right after the MLG touched down, followed by a more significant left lateral acceleration when the NLG touched down about 2 seconds later. The heading began to diverge left of the track when the NLG touched down. About 5 seconds after touchdown, the heading and lateral acceleration transitioned to the right, even though the airplane was still tracking to the left side of the runway. All of these factors are consistent with the NLG tire having been turned to the left at the time of touchdown and with the tire then skidding throughout the landing roll. Examination of the steering horn revealed that some dimensions exceeded specified tolerances, but they were slight and would have a negligible effect on the function of the steering. Examination of the steering system did not reveal any anomalies or malfunctions that would have precluded normal operation. Following the incident, the NLG tire pressure was measured at 33 psi, significantly lower than manufacturer recommendations. Given the significant crosswind component at the time of the landing, it is likely that the pilot was correcting for this crosswind component with left rudder input and did not neutralize the rudder pedals, and the NLG wheel, before NLG touchdown. Other Incidents N641WA The airplane departed the left side of the runway shortly after touchdown and came to rest in the dirt and grass adjacent to the runway after the NLG collapsed. The wind at the time of the incident was variable at 3 kts. The pilot checked the NLG tire pressure and added air 2 days before the event. The NLG tire pressure was 78 psi when measured 3 days after the event and decreased to 64 psi 8 days after the event. It is likely that the NLG tire pressure was below recommended at the time of the incident. Data from the airplane showed two distinct oscillations in lateral acceleration after NLG touchdown before the excursion to the left. The heading and track diverged during the excursion, with the heading reaching a maximum of 60º left of the track. The skid marks show the airplane in a left skid with all three tires skidding. The airplane had the new configuration steering horn installed at the time of the incident which had some dimensions out of tolerance. Examination of the steering horn did not reveal any anomalies that would have precluded normal operation. The available information suggests that the pilot over-controlled the airplane in response to the initial lateral acceleration experienced upon NLG touchdown. The low tire pressure likely contributed to the event. N831PS The pilot experienced a veer to the left during landing on runway 33, but was able to control the airplane before it departed the runway surface. The wind at the time of the incident was from 120º at 3 kts. The pilot examined the airplane after the event and finding no damage, returned to his home airport. The NLG tire pressure after this flight was 72 psi. Examination of the steering horn did not reveal any anomalies that would have precluded normal operation. The data showed a deviation to the left with a response to the right as reported by the pilot. The available evidence suggests that the low tire pressure contributed to the left veer. N115NX The first of this airplane’s three steering events occurred in December 2019 during a delivery flight performed by a manufacturer test pilot. The airplane departed the right side of runway 18 after touching down and came to rest on a taxiway. The wind at the time of the incident was from 190º at 9 kts. All tire pressures measured about 10 psi low and the steering horn pads-to-roller dimensions were significantly out of tolerance. The steering horn was replaced with a new unit but of the older configuration. The available information suggests that the tire pressure and play in the steering system contributed to the excursion. The second event occurred in June 2020 after the airplane had been purchased. During landing on runway 22, the airplane veered to the right upon NLG touchdown, but did not leave the runway surface. The wind at the time of the incident was from 210º at 11 kts. The pilot reported that he had very little time in the PA-46-600TP, but had previously owned a PA-46-350. The flight instructor onboard reported that the pilot corrected to the right, which developed into a left-right oscillation during which the pilot was applying rudder input to each of the stops. Avionics data corroborated the flight instructor’s account of the event. The available information suggests that the pilot over-controlled the airplane following the initial left veer. The third event occurred a week after the first event when the pilot was receiving training in the airplane with a flight instructor. The airplane experienced a veer to the right during landing on runway 4 and the pilot reported that the right MLG departed the paved surface. The wind at the time of the incident was from 020º at 4 kts. The pilot recalled touching down with a left drift, so he applied increasing right rudder until the airplane responded and darted right. The instructor had his feet on the rudder pedals and reported that the pilot was adding right ridder before the NLG touched down and the airplane darted right once the NLG touched down. The instructor took the flight controls and regained control of the airplane. According to the instructor, the tire pressures were normal before the flight. Avionics data corroborated the instructor’s account of the incident, with an initial slight left acceleration followed by a hard veer to the right. The available information suggests that the pilot applied right rudder before NLG touchdown instead of centering the NLG wheel. The airplane’s pilot operating handbook contains a caution that states, “In crosswind conditions, the nosewheel may not be aligned with the runway as the wheel touches down because of opposite rudder input. To prevent swerving in the direction the nosewheel is offset, the rudder must be promptly centered just as the nosewheel touches down.” Straightening the nose wheel can be challenging, especially when landing in crosswind conditions, since any amount of rudder input will also rotate the NLG wheel. The manufacturer has maintained that NLG tire pressure is critical for NLG steering control on the airplane. As the pressure decreases in the NLG tire, the contact patch with the runway increases and therefore, the friction force generated at the tire runway interface increases. The manufacturer recommends checking the tire pressure before each flight and has modified the specified pressure through service letter (SL) 1285, 1285A, and 1285B. The rake angle of the NLG was established with the first PA-46 airplane and has not changed as the airplane has changed. The NLG rake is essentially zero, with the NLG strut designed to be 90º from the airplane longitudinal axis with a very tight tolerance allowing 0.5º forward rake and zero aft rake. This zero rake angle is good for static stability and taxiing at slower speeds, but can be problematic for its dynamic stability at higher speeds. A zero or aft rake can tend to cause the NLG tire to turn sharper without any input by the pilot. Low tire pressure can exacerbate the problem. On NLG touchdown, the NLG strut will deflect aft due to spring-back, increasing the negative rake that could cause an instability. Any amount of play in the NLG steering system can result in pilots tending to overcontrol the airplane and input more rudder pedal before there is a response. The manufacturer has redesigned portions of the NLG steering system to tighten the tolerances and developed a new steering horn that attempts to minimize the play in the system by controlling the critical dimensions more closely. The new steering horn is being installed on all new airplanes after SN 4698135. For the incidents investigated, there was not one single factor that could be identified as causal, but rather a combination of factors, such as tire pressure, rake angle, tolerance stack up, pilot technique, and crosswinds that combined to result in a directional excursion.
HISTORY OF FLIGHTOn December 6, 2020, about 1420 eastern standard time, a Piper PA-46-600TP, N282ST, sustained minor damage when it was involved in an incident near Leesburg, Virginia. The pilot was not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the wind was “straight down the runway” when he landed on runway 35 at the Leesburg Executive Airport (JYO), Leesburg, Virginia. While continuing straight during the landing roll, the airplane “went careening to the left.” He stated that the right brake locked, and the right main landing gear (MLG) tire “blew” from the skidding. The pilot applied “significant” rudder and brake inputs to correct the deviation; however, he was unsuccessful, and the airplane departed the left side of the runway, coming to rest in the grass about 12 ft from the left edge of the runway and about 2,370 ft from the approach end of the runway. Data downloaded from the airplane’s Garmin G3000 Integrated Avionics System revealed a rightward lateral acceleration following touchdown immediately followed by a significant lateral acceleration to the left and a corresponding decrease in heading and track consistent with the airplane sliding. PERSONNEL INFORMATIONThe pilot reported 4,003 total hours of flight experience, with 67 hours in the incident airplane make and model. AIRCRAFT INFORMATIONThe Piper PA-46-600TP M600 is a single turbine engine, propeller-driven, low wing airplane that was certified in June 2016 (See figure 1). The incident airplane was serial number (SN) 4698111. Figure 1. Piper PA-46-600TP M600 airplane 3-view drawing. Nose Landing Gear Steering The nose landing gear (NLG) is attached to the engine mount at the upper end of the trunnion assembly by two trunnion bolts. The NLG strut assembly is installed in the trunnion assembly, where it rotates for nosewheel steering. The retract actuator is attached to the NLG trunnion assembly and engine mount to allow the NLG to retract aft into the wheel well. During retraction, the NLG strut and tire rotate 90° left through a mechanism that stows the NLG tire in a horizontal position. The NLG is steerable through a 50° arc, 20° left and 30° right of center, using the rudder pedals. Primary rudder mechanical stops are installed adjacent to the rudder sector in the empennage to limit the deflection of the rudder and thus the motion of the rudder pedals. Secondary rudder pedal mechanical stops are installed in a machined aluminum fitting aft of the steering bellcrank. The secondary stops allow for a small amount of additional rudder pedal movement, as the rudder cables stretch before the stops engage the steering bellcrank. The NLG steering horn is attached to the top of the NLG strut with three bolts. When the landing gear are extended, the right and left forward faces of the steering arm engage the right and left pads and rollers on the steering horn to transmit the linear motion of the rudder pedals to a rotational motion of the NLG strut. Steering Horn Assembly During manufacture, a steering horn assembly (part number 85154-012) was installed on M600 airplanes with SN 4698001 to 4698135. The assembly was the same as used on the M500 airplane and is attached to the NLG strut with three bolts through the base. A rub block is attached to the forward leg of the top plate, a large roller is attached to the top plate’s left leg, and a small roller is attached to the top plate’s right leg. The two steering pads and two steering rollers interface with the steering arm to provide nosewheel steering when the NLG is in the down position. The left roller should be up to 0.020 inch forward of the steering pad. The manufacturer discovered alignment issues with certain steering horn assemblies installed on airplanes with SN 4698102 and above, where the location of the steering pads and rollers were not consistent due to variances in the tolerance stack up. The alignment could be adjusted by machining the faces of the steering pads to achieve the necessary dimensional relationship between the pads and rollers. Starting at SN 4698136, the nose wheel steering horn and roller assembly was changed. The overall design of the new steering horn assembly, part number 46N32A009-001, did not change; however, the tolerances on certain critical dimensions were reduced. Maintenance History At the time of the incident, the airplane had accrued a total of 91 flight hours. The airplane received its airworthiness certificate on December 7, 2019. On January 17, 2020, the steering horn was removed from the NLG so that the steering pads could be resurfaced in accordance with the manufacturing drawing. The steering horn was reinstalled while the airplane was still at the Piper factory service center after it had accrued 5 hours total time. The airplane manufacturer’s Warrantable 1st 50-hour inspection was completed on May 20, 2020, at which time the NLG and MLG oleo struts were serviced. The airplane had accrued 25.0 hours total time at the time of the maintenance. The most recent maintenance on the airplane was work on the avionics performed on August 7, 2020, at an airplane total time of 52.1 hours. Landing Procedures According to the normal procedures section of the Pilot’s Operating Handbook (POH), pilots are cautioned to promptly center the rudder just as the nosewheel touches down in crosswind conditions to prevent swerving during landing. Figure 2. POH Normal landing procedures. METEOROLOGICAL INFORMATIONAt 1355, the recorded weather at JYO included wind from 300° at 11 knots gusting to 19 knots. The calculated (left) crosswind component was 7.1 kts gusting to 12.2 kts. AIRPORT INFORMATIONThe Piper PA-46-600TP M600 is a single turbine engine, propeller-driven, low wing airplane that was certified in June 2016 (See figure 1). The incident airplane was serial number (SN) 4698111. Figure 1. Piper PA-46-600TP M600 airplane 3-view drawing. Nose Landing Gear Steering The nose landing gear (NLG) is attached to the engine mount at the upper end of the trunnion assembly by two trunnion bolts. The NLG strut assembly is installed in the trunnion assembly, where it rotates for nosewheel steering. The retract actuator is attached to the NLG trunnion assembly and engine mount to allow the NLG to retract aft into the wheel well. During retraction, the NLG strut and tire rotate 90° left through a mechanism that stows the NLG tire in a horizontal position. The NLG is steerable through a 50° arc, 20° left and 30° right of center, using the rudder pedals. Primary rudder mechanical stops are installed adjacent to the rudder sector in the empennage to limit the deflection of the rudder and thus the motion of the rudder pedals. Secondary rudder pedal mechanical stops are installed in a machined aluminum fitting aft of the steering bellcrank. The secondary stops allow for a small amount of additional rudder pedal movement, as the rudder cables stretch before the stops engage the steering bellcrank. The NLG steering horn is attached to the top of the NLG strut with three bolts. When the landing gear are extended, the right and left forward faces of the steering arm engage the right and left pads and rollers on the steering horn to transmit the linear motion of the rudder pedals to a rotational motion of the NLG strut. Steering Horn Assembly During manufacture, a steering horn assembly (part number 85154-012) was installed on M600 airplanes with SN 4698001 to 4698135. The assembly was the same as used on the M500 airplane and is attached to the NLG strut with three bolts through the base. A rub block is attached to the forward leg of the top plate, a large roller is attached to the top plate’s left leg, and a small roller is attached to the top plate’s right leg. The two steering pads and two steering rollers interface with the steering arm to provide nosewheel steering when the NLG is in the down position. The left roller should be up to 0.020 inch forward of the steering pad. The manufacturer discovered alignment issues with certain steering horn assemblies installed on airplanes with SN 4698102 and above, where the location of the steering pads and rollers were not consistent due to variances in the tolerance stack up. The alignment could be adjusted by machining the faces of the steering pads to achieve the necessary dimensional relationship between the pads and rollers. Starting at SN 4698136, the nose wheel steering horn and roller assembly was changed. The overall design of the new steering horn assembly, part number 46N32A009-001, did not change; however, the tolerances on certain critical dimensions were reduced. Maintenance History At the time of the incident, the airplane had accrued a total of 91 flight hours. The airplane received its airworthiness certificate on December 7, 2019. On January 17, 2020, the steering horn was removed from the NLG so that the steering pads could be resurfaced in accordance with the manufacturing drawing. The steering horn was reinstalled while the airplane was still at the Piper factory service center after it had accrued 5 hours total time. The airplane manufacturer’s Warrantable 1st 50-hour inspection was completed on May 20, 2020, at which time the NLG and MLG oleo struts were serviced. The airplane had accrued 25.0 hours total time at the time of the maintenance. The most recent maintenance on the airplane was work on the avionics performed on August 7, 2020, at an airplane total time of 52.1 hours. Landing Procedures According to the normal procedures section of the Pilot’s Operating Handbook (POH), pilots are cautioned to promptly center the rudder just as the nosewheel touches down in crosswind conditions to prevent swerving during landing. Figure 2. POH Normal landing procedures. WRECKAGE AND IMPACT INFORMATIONAirplane Examination Examination of the airplane revealed impact damage to the left wingtip just aft of the navigation light and slight buckling of the upper wing skin just inboard of the wingtip and forward of the main wing spar. The right MLG tire was deflated and exhibited two flat spots, one that was worn through the tire. Examination of the preload bearings and brakes revealed no anomalies. The left MLG tire exhibited two flat spots; however, the tire was not worn through. The left MLG tire pressure measured 44.0 psi. At the time of the incident, the manufacturer specified a MLG tire pressure of 99-104 psi. The left main gear hub cap's schrader valve access door was not oriented to access the schrader valve. The NLG tire remained inflated, and the fork was deformed to the left about 10º. The right side tire wall markings were significantly abraded. The NLG tire pressure measured 33.3 psi. At the time of the incident, the manufacturer specified a NLG tire pressure of 92-97 psi. The steering horn remained attached to the top of the NLG strut and exhibited areas of chipped and cracked paint, but no mechanical damage. There was a small impact mark noted on the aft face of the left side of the steering arm that serves as the left turn mechanical stop. No anomalies to rake angle or roller gap settings were noted during the examination in reference to service letter (SL) 1286, dated August 18, 2020. Examination of the steering horn assembly at the manufacturer revealed that the left roller hole location measured 0.001-inch aft of its maximum tolerance. The right roller hole location measured 0.001-inch closer laterally to the center of the base than its maximum tolerance. The left steering pad measured 0.030-inch closer laterally to the center of the base than its maximum tolerance and the right steering pad measured 0.020-inch closer laterally to the center of the base than its maximum tolerance. All other dimensions were within the tolerances specified on the relevant manufacturing drawing(s). Runway and Ground Scars Examination Examination of the incident site revealed three distinct ground scars in the grass at the edge of the runway. At the runway departure point, the NLG ground scar was 4 ft from the right MLG ground scar and 8.8 ft from the left MLG ground scar measured perpendicular to the scars. There were distinct rubber transfer marks on the paved surface of runway 35 that matched the locations of the ground scars. The rubber transfer marks were traced back to their beginning points on the runway surface. The left MLG rubber transfer mark showed four parallel lines with spaces between, consistent with the tire tread pattern and the tires rolling with brakes applied. The marks were lighter in appearance for the first 85 ft then became much darker, consistent with heavier braking action. The right MLG rubber transfer mark showed four parallel lines with spaces between for the first 7 ft, then transitioned to a darker and wider line with no tread pattern consistent with a skidding tire. The dark, wide right MLG skid mark continued until about 60 feet from the departure point, where it transitioned to a very light mark. The NLG rubber transfer mark was a wider line of varying intensity with no tread pattern, consistent with a skidding tire. Recorded Flight Data The Garmin G3000 Integrated Avionics System on the airplane recorded certain flight parameters. Data downloaded and plotted by the manufacturer revealed the altitude, groundspeed, heading, track, pitch, and lateral acceleration data for the incident landing, shown in Figure 3. The airplane experienced an initial slight lateral acceleration to the right after the MLG touched down, followed by a more significant left lateral acceleration when the NLG touched down about 2 seconds later. The heading began to diverge left of the track when the NLG touched down. About 5 seconds after touchdown, the heading and lateral acceleration transition to the right, even though the airplane was still tracking toward the left side of the runway. Figure 3. Plot of data from N282ST incident landing. ADDITIONAL INFORMATIONOther Incidents During this investigation, the NTSB was notified of similar events involving Piper PA-46-600TP airplanes. Although these events did not meet the criteria for classification as an accident, the NTSB gathered information and performed some investigative work for comparison. N641WA Incident On January 19, 2021, about 1615 eastern standard time, a Piper PA-46-600TP, N641WA, sustained minor damage when it departed the runway during landing at Manchester Airport (MHT), Manchester, New Hampshire. The pilot and passenger were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight. The pilot reported that the airplane underwent its 50-hour inspection in late December 2020, after which he flew to Arizona, where he completed 20 hours of flight training in the airplane. The day before the event, the pilot checked the tire pressures and found them to be low. A mechanic recalled that the NLG tire pressure was about 80 psi and he added air to the tire to bring it to 92 psi. Upon landing on runway 35 at MHT, the airplane experienced a loss of directional control and a subsequent runway excursion during which the NLG collapsed. MHT airport operations examined the runway immediately following the incident and reported a dry runway and no snow or ice contamination. The wind at the time of the incident was variable at 3 kts. Data downloaded from the airplane’s Garmin G3000 Integrated Avionics System indicated that, following NLG touchdown, there were two distinct oscillations in lateral acceleration before the excursion to the left. The G3000 wheel speed sensors were not recording at the time of the incident. Examination of the runway revealed three distinct rubber transfer marks that led to two ground scars and the right MLG. All three transfer marks were dark, wide lines with no visible tread pattern, consistent with the tire's track angle while skidding. The three marks arced to the left throughout their length. The NLG mark was initially to the right of the left MLG mark and crossed over the left MLG mark about halfway along the length of the marks. The NLG tire pressure was 78 psi when measured 3 days after t
The pilot’s loss of directional control during landing in crosswind conditions. Contributing to the loss of control was the significantly underinflated nose landing gear tire.
Source: NTSB Aviation Accident Database
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