I've always worn a helmet when crop dusting in either an airplane or helicopter. Two years ago while spraying a field my engine starting spooling down without any advanced notice. I was headed for a large area of trees, which were probably 85 to 100 feet high, so I pulled up and turned left 90 degrees out over another field and proceeded to land. As luck would have it we had just received 8 inches of rain so the field I'm landing in is wet to say the least. The first part of the rollout was not bad but as the wheels began to sink in the mud the tail started coming up. We were pretty slow by then but not enough to keep from flipping over on her back.
We fly Ayres Turbo Thrushes which have enclosed cockpits. As the bird flopped on her back the cockpit stuck down in the mud and crushed the top of the fiberglass canopy. The doors of a Thrush let down; but, now they were stuck about six inches in the mud. I released my harnes and fell into the top of the cab and proceeded to get the left door off. Each side has an emergency release which alows the door to come off the hinge pins. Most crop dusters have ample room at the bottom of the cockpit where you sit but if you flip it over, it's mighty small up where your head normally is. With the top of the door firmly stuck in the mud I had to bend the door over enough to crawl out all the while praying very hard that she wouldn't catch fire. Time slows down when your scared but it seemed like it took ten minutes to get out. After I got out on my hands and knees I was covered with mud from head to toe. I knew there was a little bar about a half mile away and believe it or not bars are open in Louisiana at 8:00 in the morning.
The cause of the engine failure was the torque sensor fuel pump gear broke in half which caused the fire to go out. Funny thing about engine failures, the insurance company will pay to fix the airplane but not the engine. A pilot can run out of gas and they'll fix the whole machine; but, let part of the engine fail and it's no longer covered.
Getting back to helmets. When we flipped over on our back the fiberglass and mud shoved down on my head pretty good. I didn't have any injury's but that next winter when the helmet was sent in for it's semiannual refurb the shell was cracked. I wear a Flight Suit helmet, that is form fitted to my head, and they do not repair shells. So, I had to spend several hundred dollars for a new helmet. In the end, I'm sure glad I had one on to start with.