PA18 pilot reported his aircraft taxied unattended into a parked aircraft after he walked away from ...

Attributes
ACN	1387577
Time
Date	201609
Local Time Of Day	0601-1200
Place
Locale Reference	ZZZ.Airport
State Reference	US
Environment
Light	Daylight
Aircraft 1
Make Model Name	PA-18/19 Super Cub
Operating Under FAR Part	Part 91
Flight Phase	Parked
Flight Plan	None
Aircraft 2
Make Model Name	Small Aircraft
Operating Under FAR Part	Part 91
Flight Phase	Parked
Component
Aircraft Component	Engine
Person 1
Function	Single Pilot Pilot Flying
Qualification	Flight Crew Commercial
Experience	Flight Crew Last 90 Days 185 Flight Crew Total 1650 Flight Crew Type 950
Events
Anomaly	Ground Event / Encounter Aircraft Ground Event / Encounter Loss Of Aircraft Control

Narrative:

In preparation for a formation flight banner flight; my aircraft was parked in the grass next to the fuel pump. My coworker had his aircraft parked off to my left and the [other aircraft] was parked off to my aircraft's right. After starting the aircraft my coworker left his plane running and ran to get my attention to help him with something in his plane. Seeing his aircraft running and knowing that we were on a tight time schedule and knowing my plane would be hard to restart if I did turn it off. Being in the grass I left the plane running and helped him with his problem for about one minute or so. After helping him I turned around to head back to my plane and noticed it starting to roll forward and to the right towards the [other aircraft]. My coworker and I ran and grabbed the tail just as it hit the propeller of the parked [aircraft]. Knowing now I should have shut the aircraft down before walking away from it.

Original NASA ASRS Text

Title: PA18 pilot reported his aircraft taxied unattended into a parked aircraft after he walked away from it with the engine still running.

Narrative: In preparation for a formation flight banner flight; my aircraft was parked in the grass next to the fuel pump. My coworker had his aircraft parked off to my left and the [other aircraft] was parked off to my aircraft's right. After starting the aircraft my coworker left his plane running and ran to get my attention to help him with something in his plane. Seeing his aircraft running and knowing that we were on a tight time schedule and knowing my plane would be hard to restart if I did turn it off. Being in the grass I left the plane running and helped him with his problem for about one minute or so. After helping him I turned around to head back to my plane and noticed it starting to roll forward and to the right towards the [other aircraft]. My coworker and I ran and grabbed the tail just as it hit the propeller of the parked [aircraft]. Knowing now I should have shut the aircraft down before walking away from it.

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.