N401WS

HISTORY OF FLIGHTOn October 31, 2012, about 0930 eastern daylight time, a Piaggio P180 Avanti airplane, N401WS, exited the runway while landing at the Boyne City Municipal airport (N98) Boyne City, Michigan. The airline transport pilot and commercial pilot were not injured. The airplane sustained substantial damage. The airplane was registered to Ann Arbor Aviation Partners LLC and operated by Flagship Private Air under the provisions of 14 Code of Federal Regulations Part 91 as a positioning flight. Instrument meteorological conditions prevailed for the flight and an instrument flight rules (IFR) flight plan was filed. The flight originated from the Willow Run Airport (KYIP) about 0820.

The pilot stated that the nose wheel steering was not engaged during the landing, and that after the airplane touched down, it made an uncommanded left turn. The pilot used landing gear braking and reverse thrust to control the airplane but it still continued to veer left and continued off of the runway. The airplane struck the airport perimeter fence and a tree and came to rest.

The airplane was moved to a secured location at N98 for further examination. The initial investigative team met at N98 and conducted a postaccident examination of the nose wheel steering system and its associated components. After the examination, the nose landing gear was removed and sent to the manufacturer's facility in England for further examination and testing. PERSONNEL INFORMATIONThe pilot, age 63, held an airline transport pilot certificate with airplane single engine land, multi-engine land, rotorcraft-helicopter, and instrument airplane ratings. The pilot was issued a first class medical certificate on July 18, 2012 with the limitation to wear corrective lenses. He reported that he had accumulated 11,506 total flight hours, 665 of which were in the accident airplane make and model. He had accumulated 85 flight hours in the previous 90 days. He met the currency requirements for IFR flying.

The co-pilot, age 28, held a commercial pilot certificate with airplane single engine land, multi-engine land, and instrument airplane ratings. He was also a certified flight instructor for single engine land airplanes. He was issued a first class medical certificate on March 12, 2012 with no limitations. He reported that he had accumulated 645 total flight hours, 109 of which were in the accident airplane make and model. He had accumulated 33 flight hours in the previous 90 days. He also met the currency requirements for IFR flying. AIRCRAFT INFORMATIONAccording to the aircraft maintenance logbooks the airplane was in compliance with an Approved Aircraft Inspection Program (AAIP) and the most recent inspections were competed on October 24, 2012.

The accident flight was reported by the operator to be the third flight following the airplane's completion of a D-Check, which included an overhaul of the nose landing gear, both main landing gears, and both engines. The Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2009-21-08 Rev 1 was last completed and signed off by the operator on October 24, 2012. The reason for the AD was listed as:

Some cases of uncommanded steering action were observed, while the steering system was switched off. A leakage in the Steering Select/Bypass Valve, installed in the Steering Manifold, when closed, is suspected to have caused the uncommanded steering.

The nose landing gear and steering manifold were overhauled by Advantage Aviation Technologies II, LLC (AAT) on September 12, 2012, and August, 17, 2012 respectively. According to the AAT work order, the steering manifold was overhauled in accordance with Component Maintenance Manual (CMM) 32-50-50, Revision 6.

The aircraft maintenance logbook entry dated October 24, 2012, revealed that the nose landing gear was re-installed on the accident airplane. METEOROLOGICAL INFORMATIONAt 0914, the automated weather report for Charlevoix, Michigan, which was 13 miles northwest of the accident site, reported: wind from 360 degrees at 14 knots, gusting to 24 knots, visibility 7 miles, sky condition overcast clouds at 1,600 feet, temperature 39 degrees Fahrenheit (F), dew point 36 degrees F, and altimeter setting 29.69 inches of mercury. AIRPORT INFORMATIONAccording to the aircraft maintenance logbooks the airplane was in compliance with an Approved Aircraft Inspection Program (AAIP) and the most recent inspections were competed on October 24, 2012.

The accident flight was reported by the operator to be the third flight following the airplane's completion of a D-Check, which included an overhaul of the nose landing gear, both main landing gears, and both engines. The Federal Aviation Administration (FAA) Airworthiness Directive (AD) 2009-21-08 Rev 1 was last completed and signed off by the operator on October 24, 2012. The reason for the AD was listed as:

Some cases of uncommanded steering action were observed, while the steering system was switched off. A leakage in the Steering Select/Bypass Valve, installed in the Steering Manifold, when closed, is suspected to have caused the uncommanded steering.

The nose landing gear and steering manifold were overhauled by Advantage Aviation Technologies II, LLC (AAT) on September 12, 2012, and August, 17, 2012 respectively. According to the AAT work order, the steering manifold was overhauled in accordance with Component Maintenance Manual (CMM) 32-50-50, Revision 6.

The aircraft maintenance logbook entry dated October 24, 2012, revealed that the nose landing gear was re-installed on the accident airplane. WRECKAGE AND IMPACT INFORMATIONThe airplane veered off the left side of the runway, continued through short grass and impacted the airport perimeter fence and a tree. This was verified by the tire skid marks on the runway and the tire marks in the grass leading to the airplane, which came to rest upright next to the fence. The nose wheel impacted the ground and the wheels remained fully deflected to the left. ADDITIONAL INFORMATIONCockpit Voice Recorder (CVR)

The airplane's CVR was reviewed for the accident flight and no anomalies were noted.

Similar Occurrence – CEN13IA270

On April 24, 2013, about 1720 eastern daylight time, a Piaggio P180 airplane, N139SL, received minor damage during a runway excursion at the St. Petersburg-Clearwater International Airport (KPIE), Clearwater, Florida. The nose landing gear system had been recently overhauled by the same overhaul facility. The NTSB's probable cause of that incident was listed as: "The failure of the nose landing gear steering manifold during landing, which resulted in an uncommanded and uncontrollable right turn, and the overhaul facility's improper overhaul of the nose landing gear steering manifold." TESTS AND RESEARCHInitial Nose Landing Gear Testing:

The aircraft was moved into an unheated hanger located at Boyne City Municipal Airport prior to NTSB arrival on scene. The airplane was examined at this location on November 27-28, 2012. Recovery personnel stated they turned off the master battery before the aircraft was removed and that the electrical and hydraulic systems were not energized during the recovery process. They also stated that the steering pin was found engaged but was removed to facilitate aircraft recovery. The nose landing gear (NLG) system was examined and tested for proper function by the investigative team.

The left and right nose tires were both pressurized at 52 psi. (NOTE: The ambient air temperature was not recorded. For reference, Bellaire, Michigan, was located approximately 20 miles southeast of Boyne City and recorded a high of 33 degrees Fahrenheit and a low of 25 degrees Fahrenheit during the dates of November 27 and 28, 2012.) The pilot stated that during the preflight checks on the day of the accident all tire pressures were in the normal range. The Aircraft Maintenance Manual, Section 12-10-04, dated Oct 30/09, states that the nose landing gear tire pressure should be 64 +/- 2 psi. The nose assembly shock strut pressure was approximately 98 psi with weight off wheels. The placard on the aircraft states the pressure should be 120 +/- 10 psi. Both nose wheel assemblies spun freely using hand force when the nose of the airplane was on jacks. There was no significant damage identified on either tire.

A ground power unit supplying 28 volts was connected to the aircraft. An air compressor supplying 30 psi air was connected to the hydraulic pump reservoir to prevent cavitation within the hydraulic system. The nose wheel steering (NWS) system and hydraulics were verified to be in the off position. With the nose wheel centered and on the ground the steering pin was removed. The hydraulic system was then turned on (the NWS system remained electrically powered off) and the NWS actuator began to extend. The actuator extended to a position of approximately 1.5 inch chrome extension.

The steering pin was then installed and with hydraulics on and the NWS system electrically powered off, the actuator did not move. The steering pin was again removed and with hydraulics on and the NWS system electrically powered off, the actuator extended at a rate of approximately 1 inch per minute.

Nose Landing Gear Testing per Service Bulletin 80-0249:

During investigative testing following the accident, the accident airplane was subjected to the SB in its entirety despite some observed failures which would have concluded the test before its completion.

Piaggio released Service Bulletin (SB) 80-0249 (Rev 1 dated 27/05/2009 with original issue dated 18/06/2008) after an incident involving uncommanded movement of the nose wheel. The reason for the SB stated:

One case of poor sealing of the Steering Select / Bypass Valve (installed in the Steering Manifold) was observed, resulting in an uncommanded steering action. The aim of the procedure described in this Service Bulletin is to verify the leakage proofness of the Steering Manifold when the system ...