Experimental aircraft pilot reported a gear collapse on takeoff due to a faulty gear lock spring.

Attributes
ACN	1580795
Time
Date	201809
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	Amateur/Home Built/Experimental
Operating Under FAR Part	Part 91
Flight Phase	Takeoff
Route In Use	Direct
Flight Plan	VFR
Component
Aircraft Component	Gear Down Lock
Person 1
Function	Single Pilot
Qualification	Flight Crew Private
Experience	Flight Crew Last 90 Days 7 Flight Crew Total 616 Flight Crew Type 28
Events
Anomaly	Aircraft Equipment Problem Critical Ground Event / Encounter Other / Unknown

Narrative:

Gear collapsed during takeoff; due to gear lock disengaging while bouncing on the runway. Found out later that retaining spring to keep lock engaged was missing. This spring is not on annual nor on preflight check list. Strongly recommend to add on both list and check function on regular basis.

Original NASA ASRS Text

Title: Experimental aircraft pilot reported a gear collapse on takeoff due to a faulty gear lock spring.

Narrative: Gear collapsed during takeoff; due to gear lock disengaging while bouncing on the runway. Found out later that retaining spring to keep lock engaged was missing. This spring is not on annual nor on preflight check list. Strongly recommend to add on both list and check function on regular basis.

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.