N89MA

HISTORY OF FLIGHTOn July 3, 2020, about 1157 eastern daylight time, a Piper PA-46-600TP, N89MA, was substantially damaged when it was involved in an accident near Titusville, Florida. The pilot and two passengers were not injured. The airplane was operated as a Title 14 Code of Federal Regulations Part 91 personal flight.

The pilot reported that, although the flight from Albert Whitted Airport (SPG), St Petersburg, Florida, to Space Coast Regional Airport (TIX), Titusville, Florida, encountered turbulence, it was otherwise uneventful with no anomalies noted. He added that, just before touchdown at TIX, “the airplane veered left of centerline and he released some of his crosswind correction yet still landed about 3 to 4 ft left of centerline.” When the two main landing gear (MLG) touched down, the airplane started to veer left, so he relaxed the rudder pressure.

As soon as the nose landing gear (NLG) touched down, the airplane started to veer right. He attempted to correct the veer by applying left aileron and rudder, as well left and right brakes; however, the airplane did not respond. He continued applying left rudder and brakes as the airplane moved toward the right side of the runway, but the airplane still did not respond. The airplane then exited the right side of the runway and skidded sideways through the grass, which resulted in the left wing and propeller striking the ground and substantial damage to the wing. The airplane came to rest about 100 ft from the runway edge

Data downloaded from the airplane’s Garmin G3000 Integrated Avionics System for the accident flight indicated that it was started on the ramp at SPG and that, before takeoff, the airplane turned right 70° on the ramp, left 50° onto taxiway D, right 80° onto runway 18, left 80° onto runway 7, and right 180° to line up on runway 25. Shortly after the MLG touched down during landing at TIX, at an airspeed of about 73 knots, the heading and track began to diverge and the lateral acceleration increased. The heading and track divergence continued for the remainder of the ground roll.

AIRCRAFT INFORMATIONNose Landing Gear Steering

The 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, 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 bell-crank. 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 part number 85154-012 steering horn was installed. The steering horn 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 with the NLG in the down position. The left roller should be up to 0.020 inch forward of the steering pad. Piper discovered alignment issues with certain steering horn assemblies installed on airplanes, including the accident airplane, 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.

Accident Airplane Maintenance History

Review of maintenance records revealed that the airplane received its airworthiness certificate on December 7, 2019. On January 17, 2020, the airframe manufacturer reworked the steering horn to align the steering pad faces with the rollers, and it was then reinstalled in the airplane before delivery. The pilot purchased the airplane in June 2020, at which time it had accumulated about 23 hours of total flight time.

After accruing 48.1 hours of flight time, the airplane underwent a 50-hour maintenance interval, which was completed on July 1, 2020. During the maintenance the left MLG strut and tire were replaced, and the MLG alignment and NLG squat switch were adjusted. Review of data from the airplane’s avionics unit revealed that, after the maintenance was completed, four flights were conducted in the airplane. The accident occurred upon landing after the fourth flight. The data also revealed that the airplane made multiple left and right turns during taxi operations before and after each flight. The pilot reported that there was no evidence of tow exceedance during his preflight inspection of the airplane on the day of the accident flight.

Airplane Towing History and Guidance

The airplane could be maneuvered on the ground by power equipment using a tow bar attached to the NLG axle. The airplane manufacturer had established turn limits for towing, and a placard installed on the lower end of the NLG trunnion assembly limits turning to about 20° right and left. Corresponding red lines on the NLG strut allow the operator to see the relationship between the turn angle of the NLG strut and the towing limits (see figure 1).

Figure 1 - NLG turn limit placard.

The Pilot’s Operating Handbook, Section 8, “Handling, Servicing and Maintenance,” contained a caution about towing, which stated, “When towing with power equipment, do not turn the nose gear beyond its steering limit in either directions, as this will result in damage to the nose gear and steering mechanism”. Similar cautions were contained in the Aircraft Maintenance Manual and a flight training manual.

If the NLG is externally turned beyond the left or right placard limits, mechanical stops will engage where portions of the NLG and steering mechanism contact. If turned beyond the right limits, a machined stop on the lower portion of the rotating strut assembly will contact a machined stop on the lower end of the stationary trunnion assembly. The right stops will engage when the NLG tire is turned right about 36°. Further, turning right may damage the machined stops and will load the strut-trunnion interface; however, it will not affect the steering arm or steering horn. If turned beyond the left limit, the steering arm left flange aft face will contact the steering arm mount plate on the engine mount. The left stops will engage when the NLG tire is turned about 30.5° left. Further, turning left may damage the steering arm and the three bolts that attach the steering horn assembly to the top of the NLG strut. The rudder primary and secondary mechanical stops do not allow the mechanical turn limit stops to be engaged through pilot rudder inputs.

The pilot stated that he was aware of the towing limitations on the airplane. The airplane was towed six times at his home airport, SPG, and he witnessed all the towing operations except when the airplane was in maintenance. It could not be determined if the airplane was towed during maintenance or, if so, how many times.

AIRPORT INFORMATIONNose Landing Gear Steering

The 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, 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 bell-crank. 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 part number 85154-012 steering horn was installed. The steering horn 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 with the NLG in the down position. The left roller should be up to 0.020 inch forward of the steering pad. Piper discovered alignment issues with certain steering horn assemblies in...