We watched as the Kitfox struggled to land. The crosswind was high and the pilot decided to go around. We breathed sighs of relief until the pilot came around again and struggled once again, determined to get on the ground. It was always interesting to sit on the FBO porch and watch the airplanes. Especially on a day like today—sunny, warm and gusty. Very gusty.
We watched the airplane trying to plant itself on the runway. The pilot lost control. The airplane ran off the runway and into high grass by the lake. “Uh oh.”
We heard the engine quit and then start again. The Kitfox came sturdily out of the tall bushes and taxied up to the FBO. We recognized the new pilot and walked out to the airplane. The prop was scuffed on both blades. “Whew. It doesn’t look bad!” exclaimed the pilot, inspecting the prop. “Just needs a little polish.”
“Hold on,” I said. “Did the grass bring the rpm down?” He said: “It got caught and actually stopped. But it started again, so how bad could it be?”
How Bad?
Bad. Here’s what Rotax has to say in its service letters: “Any cases in which the engine is operating and the propeller impacts an object which causes a considerable drop in engine rpm” is considered a prop strike. “Propeller strikes on ground or contact with various objects can result in engine and/or component damage even if the propeller may continue to rotate. Such damage may progress to engine failure…”
And it gets worse. It’s not just the prop that needs to be inspected; it’s also the engine.
According to the Rotax 912 service bulletin, this is considered a prop strike and involves a visual inspection of the gearbox housing, prop flange runout measurement and gearbox removal and inspection plus a crank inspection.
It’s not just Rotax. Continental and Lycoming have also published very thorough definitions of a prop strike. Continental says that a prop strike is “any incident while the engine is operating in which the propeller makes contact with any object that results in a loss of engine rpm. Propeller strikes against the ground or any object can cause engine and component damage even though the propeller may continue to rotate. This damage can result in catastrophic engine failure.” Sound familiar?
We recently watched an RV-8A begin taxiing from the ramp at the maintenance shop nearby. Before we could alert the pilot, a rigid tow bar assembly still attached to the nosewheel started bouncing on the asphalt. There was a “bing-bang” noise as the very edge of the prop caught the bar. The pilot immediately realized the problem and shut down. The accident bent the tips back about a half an inch. A prop strike? Absolutely. But the owner didn’t see it that way. He had the airplane towed back to the maintenance facility where he told the mechanic, “Get me another prop so I can get home, please.”
It’s a good situation if you’ve never faced making this decision about a prop strike; if it happens to you, pull out the engine manuals and service bulletins. If you’re away from home, get help to ascertain whether the airplane can be flown, rather than risk engine failure. And remember this: There is no such thing as a “minor prop strike.” This reality goes along with the joys of aircraft operation and we all should accept that there are no shortcuts to safety along the way.
