After a tailwheel bolt had broken during taxi; a pilot of a maule M-7 aircraft was later informed by...

Narrative:

Tailwheel bolt broke during taxi. This resulted in tailwheel detaching from spring. Taxi was at a brisk walk speed. Aircraft stopped straight ahead with no jostling or injury to pilot or passenger. The bolt in question is a 7/16' of an inch eyebolt. It broke at the shoulder. This hardware is part of a tailwheel company's maule aircraft supplemental type certificate/ parts manufacturer approval (stc/pma) tailwheel upgrade; aftermarket tailwheel. This bolt may have failed because of fatigue or manufacturing defect; I don't know. The tailwheels on back country aircraft are a high stress area [of the aircraft] that takes a lot of pounding in dirt strip use. I will notify the tailwheel company of this event. This may be a rare event; but if a trend were to develop there are easy fixes to helping prevent this problem. Myself; I will go to a standard hex bolt as I think it may be stronger. I will also replace this bolt with each change of the tailwheel spring; which is done periodically due to fatigue sagging.

Original NASA ASRS Text

Title: After a tailwheel bolt had broken during taxi; a pilot of a Maule M-7 aircraft was later informed by other Owner/Operators that the tailwheel Manufacturer had previously issued a larger bolt for attaching the tailwheel to the spring assembly.

Narrative: Tailwheel bolt broke during taxi. This resulted in tailwheel detaching from spring. Taxi was at a brisk walk speed. Aircraft stopped straight ahead with no jostling or injury to pilot or passenger. The bolt in question is a 7/16' of an inch eyebolt. It broke at the shoulder. This hardware is part of a tailwheel Company's Maule aircraft Supplemental Type Certificate/ Parts Manufacturer Approval (STC/PMA) tailwheel upgrade; aftermarket tailwheel. This bolt may have failed because of fatigue or manufacturing defect; I don't know. The tailwheels on back country aircraft are a high stress area [of the aircraft] that takes a lot of pounding in dirt strip use. I will notify the tailwheel Company of this event. This may be a rare event; but if a trend were to develop there are easy fixes to helping prevent this problem. Myself; I will go to a standard hex bolt as I think it may be stronger. I will also replace this bolt with each change of the tailwheel spring; which is done periodically due to fatigue sagging.

Data retrieved from NASA's ASRS site as of July 2013 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.

Attributes
ACN	1125923
Time
Date	201310
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Daylight
Aircraft 1
Make Model Name	M-7
Operating Under FAR Part	Part 91
Flight Phase	Taxi
Flight Plan	None
Component
Aircraft Component	Tail Wheel
Person 1
Function	Pilot Flying Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 10 Flight Crew Total 440 Flight Crew Type 240
Events
Anomaly	Aircraft Equipment Problem Critical Ground Event / Encounter Ground Strike - Aircraft

After a tailwheel bolt had broken during taxi; a pilot of a maule M-7 aircraft was later informed by other owner/operators that the tailwheel manufacturer had previously issued a larger bolt for attaching the tailwheel to the spring assembly.