PA25 pilot experiences a tail wheel malfunction when the tail is lowered to the runway after landing...

Attributes
ACN	941451
Time
Date	201103
Local Time Of Day	1201-1800
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	PA-25 Pawnee
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	None
Flight Plan	None
Component
Aircraft Component	Tail Wheel
Person 1
Function	Single Pilot Captain Pilot Flying
Qualification	Flight Crew Multiengine Flight Crew Commercial Flight Crew Instrument
Experience	Flight Crew Last 90 Days 25 Flight Crew Total 1392 Flight Crew Type 950
Events
Anomaly	Aircraft Equipment Problem Critical Ground Excursion Runway Inflight Event / Encounter Loss Of Aircraft Control

Narrative:

Pilot performed a wheel landing touching down around 45-50 mph (commented on by onlookers as a 'greaser' and perfectly aligned). Upon bringing the stick back to secure the tail wheel to the ground around 25-30 mph aircraft immediately and violently pulled to the right leaving the 25 ft wide asphalt landing surface and ground looped 270 degrees on the adjacent grass/dirt landing strip. Rudder and stick inputs were not successful in recovering. Proper aileron/stick inputs subsequently kept the ground loop 'flat' therefore no ensuing and damage to the aircraft. Winds at the time were light and variable; and also referred to as calm. Aircraft malfunction was investigated by chief pilot/mechanic as possible cause. Upon disassembly of the scott 3200 tail wheel; it was found that a notch was created internally on the rear portion of control arm hub. This 'notch' caused the tail wheel to lock in a 'reverse' direction and offset. This tail wheel malfunction caused the ground loop and no pilot input/actions were capable of breaking the tail wheel free and allowing directional control to be maintained during landing roll out. The subsequent severity of the ground loop caused the tail wheel to break free towards the end of the event.

Original NASA ASRS Text

Title: PA25 pilot experiences a tail wheel malfunction when the tail is lowered to the runway after landing; causing a ground loop and runway excursion.

Narrative: Pilot performed a wheel landing touching down around 45-50 MPH (commented on by onlookers as a 'greaser' and perfectly aligned). Upon bringing the stick back to secure the tail wheel to the ground around 25-30 MPH aircraft immediately and violently pulled to the right leaving the 25 FT wide asphalt landing surface and ground looped 270 degrees on the adjacent grass/dirt landing strip. Rudder and stick inputs were not successful in recovering. Proper aileron/stick inputs subsequently kept the ground loop 'flat' therefore no ensuing and damage to the aircraft. Winds at the time were light and variable; and also referred to as calm. Aircraft malfunction was investigated by chief pilot/mechanic as possible cause. Upon disassembly of the Scott 3200 tail wheel; it was found that a notch was created internally on the rear portion of control arm hub. This 'notch' caused the tail wheel to lock in a 'reverse' direction and offset. This tail wheel malfunction caused the ground loop and no pilot input/actions were capable of breaking the tail wheel free and allowing directional control to be maintained during landing roll out. The subsequent severity of the ground loop caused the tail wheel to break free towards the end of the event.

Data retrieved from NASA's ASRS site as of April 2012 and automatically converted to unabbreviated mixed upper/lowercase text. This report is for informational purposes with no guarantee of accuracy. See NASA's ASRS site for official report.