Narrative:

The problems occurred during the landing phase. We observed a left crosswind; which had a slight headwind component as we flew past the wind sock and wind T. We used the active runway with several planes landing on that runway in the previous few minutes. Touch down went smoothly; and we began tracking straight. However; we soon caught a gust from the left as the wind shifted to a quartering tailwind. I applied full right rudder and with no response added a small amount of right brake. As the brake was added; a second pilot in the rear seat; with many hours in type was not a PIC and could not be as he did not hold a medical; increased the throttle to full. This sudden; uncommunicated increase of throttle with full rudder; and slight brake inputs; resulted in a large; unrecoverable over correction to the right; ending in a ground loop to the right. Upon the plane leaving the runway and going into an adjacent a significant side load was put in the left main gear. This side load; coupled with soft sandy soil; caused the left main to dig into the ground causing it to quickly snap at the indent to secure a strap which kept the brake line in place; instead of the plane continuing its rotation. I feel that the gust; with its shift to a quartering tailwind instead of either direct crosswind or quartering headwind; is what allowed this situation to begin. However; this alone did not lead to the ground loop. This was caused by two pilots trying to fix the same problem at the same time in different ways with out it being communicated. There was no exchange of control; but rather two pilots trying to land at the same time.

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Original NASA ASRS Text

Title: A C-305 Bird Dog was ground looped and the left strut broken because the two pilots were attempting to land the aircraft at the same time. The low-time PIC in the front was overridden by a high-time non PIC in the back and the combined inputs resulted in the loss of control.

Narrative: The problems occurred during the landing phase. We observed a left crosswind; which had a slight headwind component as we flew past the wind sock and wind T. We used the active runway with several planes landing on that runway in the previous few minutes. Touch down went smoothly; and we began tracking straight. However; we soon caught a gust from the left as the wind shifted to a quartering tailwind. I applied full right rudder and with no response added a small amount of right brake. As the brake was added; a second pilot in the rear seat; with many hours in type was not a PIC and could not be as he did not hold a medical; increased the throttle to full. This sudden; uncommunicated increase of throttle with full rudder; and slight brake inputs; resulted in a large; unrecoverable over correction to the right; ending in a ground loop to the right. Upon the plane leaving the runway and going into an adjacent a significant side load was put in the left main gear. This side load; coupled with soft sandy soil; caused the left main to dig into the ground causing it to quickly snap at the indent to secure a strap which kept the brake line in place; instead of the plane continuing its rotation. I feel that the gust; with its shift to a quartering tailwind instead of either direct crosswind or quartering headwind; is what allowed this situation to begin. However; this alone did not lead to the ground loop. This was caused by two pilots trying to fix the same problem at the same time in different ways with out it being communicated. There was no exchange of control; but rather two pilots trying to land at the same time.

Data retrieved from NASA's ASRS site as of April 2012 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.