Aeronca 11AC pilot reported the left main gear collapsed due to a missing gear part.

Attributes
ACN	1747554
Time
Date	202006
Local Time Of Day	1801-2400
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Flight Conditions	VMC
Light	Dusk
Aircraft 1
Make Model Name	Bellanca Aircraft Corp Undifferentiated or Other Model
Operating Under FAR Part	Part 91
Flight Phase	Landing
Route In Use	Visual Approach
Flight Plan	None
Component
Aircraft Component	Main Gear
Person 1
Function	Single Pilot
Qualification	Flight Crew Commercial Flight Crew Instrument Maintenance Powerplant Maintenance Airframe Maintenance Inspection Authority
Experience	Flight Crew Last 90 Days 35 Flight Crew Total 2535 Flight Crew Type 47
Events
Anomaly	Aircraft Equipment Problem Critical Ground Event / Encounter Loss Of Aircraft Control

Narrative:

Ground loop occurred after landing and the collapse of the left main landing gear. The contributing factor that caused my loss of control and the resulting ground loop was a broken/missing (was not found) bolt in the left landing gear attach point. There were no injuries. There was no damage to property. Minor damage occurred to the landing gear center attach bracket and the left wheel. There was no damage to the wings or tail surfaces. There was no prop strike. The plane did not cause any traffic disruptions or airport closure. In retrospect; this was could have been prevented if I had caught the broken/missing bolt during preflight. On a positive note; landing this aircraft at the appropriate; recommended speed helped prevent this ground loop from being a violent landing.

Original NASA ASRS Text

Title: Aeronca 11AC Pilot reported the left main gear collapsed due to a missing gear part.

Narrative: Ground loop occurred after landing and the collapse of the left main landing gear. The contributing factor that caused my loss of control and the resulting ground loop was a broken/missing (was not found) bolt in the left landing gear attach point. There were no injuries. There was no damage to property. Minor damage occurred to the landing gear center attach bracket and the left wheel. There was no damage to the wings or tail surfaces. There was no prop strike. The plane did not cause any traffic disruptions or airport closure. In retrospect; this was could have been prevented if I had caught the broken/missing bolt during preflight. On a positive note; landing this aircraft at the appropriate; recommended speed helped prevent this ground loop from being a violent landing.

Data retrieved from NASA's ASRS site 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.