A tailwheel aircraft ground looped in a crosswind.

Attributes
ACN	243237
Time
Date	199306
Day	Sun
Local Time Of Day	1201 To 1800
Place
Locale Reference	airport : int
State Reference	NC
Altitude	agl bound lower : 0 agl bound upper : 0
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Operator	general aviation : personal
Make Model Name	Small Aircraft, High Wing, 1 Eng, Fixed Gear
Flight Phase	landing other
Flight Plan	None
Person 1
Affiliation	Other
Function	flight crew : single pilot
Qualification	pilot : commercial
Experience	flight time last 90 days : 29 flight time total : 1250 flight time type : 77
ASRS Report	243237
Events
Anomaly	other anomaly other anomaly other
Independent Detector	other flight crewa
Resolutory Action	none taken : insufficient time
Consequence	other
Supplementary
Primary Problem	Flight Crew Human Performance
Air Traffic Incident	Pilot Deviation

Narrative:

Flying from rear seat in tailwheel aircraft. Asphalt runway. Wind about 8 KTS per windsock, 6 KTS per tower. Variable from about 20 degrees to the left of centerline ahead to 20 degrees to left of centerline at rear. When made contact for good 3 point landing, tailwheel shimmy when stick held to rear was experienced. As pressure released from stick, aircraft began to turn to left into wind. Right ruder applied for correction. Unfortunately, this was at the point where tailwheel airplane is neither flying nor driving. Control forces were insufficient to prevent ground loop. Right spring steel landing gear strut bent inward above wheel due to traction of tire on asphalt. Aircraft rotated about 90 degrees to the left. From what I have read and seen, this is a risk inherent in tailwheel aircraft. I had previously noticed the tailwheel shimmy, but it appeared to have been reduced substantially by tightening the lug nut at the end of the axle. I elected to use rudder and not apply power. On grass this would have been more effective. Better visibility and more forward center of gravity from front seat may have helped. The crosswind was well within the component. However, the shifting nature of same close to the ground apparently was sufficient to cause the unctlability to come at a most inopportune moment. In retrospect, power should have been added and tail raised at first tailwheel shimmy.

Original NASA ASRS Text

Title: A TAILWHEEL ACFT GND LOOPED IN A XWIND.

Narrative: FLYING FROM REAR SEAT IN TAILWHEEL ACFT. ASPHALT RWY. WIND ABOUT 8 KTS PER WINDSOCK, 6 KTS PER TWR. VARIABLE FROM ABOUT 20 DEGS TO THE L OF CTRLINE AHEAD TO 20 DEGS TO L OF CTRLINE AT REAR. WHEN MADE CONTACT FOR GOOD 3 POINT LNDG, TAILWHEEL SHIMMY WHEN STICK HELD TO REAR WAS EXPERIENCED. AS PRESSURE RELEASED FROM STICK, ACFT BEGAN TO TURN TO L INTO WIND. R RUDER APPLIED FOR CORRECTION. UNFORTUNATELY, THIS WAS AT THE POINT WHERE TAILWHEEL AIRPLANE IS NEITHER FLYING NOR DRIVING. CTL FORCES WERE INSUFFICIENT TO PREVENT GND LOOP. R SPRING STEEL LNDG GEAR STRUT BENT INWARD ABOVE WHEEL DUE TO TRACTION OF TIRE ON ASPHALT. ACFT ROTATED ABOUT 90 DEGS TO THE L. FROM WHAT I HAVE READ AND SEEN, THIS IS A RISK INHERENT IN TAILWHEEL ACFT. I HAD PREVIOUSLY NOTICED THE TAILWHEEL SHIMMY, BUT IT APPEARED TO HAVE BEEN REDUCED SUBSTANTIALLY BY TIGHTENING THE LUG NUT AT THE END OF THE AXLE. I ELECTED TO USE RUDDER AND NOT APPLY PWR. ON GRASS THIS WOULD HAVE BEEN MORE EFFECTIVE. BETTER VISIBILITY AND MORE FORWARD CTR OF GRAVITY FROM FRONT SEAT MAY HAVE HELPED. THE XWIND WAS WELL WITHIN THE COMPONENT. HOWEVER, THE SHIFTING NATURE OF SAME CLOSE TO THE GND APPARENTLY WAS SUFFICIENT TO CAUSE THE UNCTLABILITY TO COME AT A MOST INOPPORTUNE MOMENT. IN RETROSPECT, PWR SHOULD HAVE BEEN ADDED AND TAIL RAISED AT FIRST TAILWHEEL SHIMMY.

Data retrieved from NASA's ASRS site as of July 2007 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.