“What’s wrong?” asked Ned.
“Oil feed supply,” was the short answer. “You run the plane, Ned, and I’ll take the pipe down and clean it. We can run on one line while I’m working on the other.”
It was a few minutes later, when Tom had the pipe uncoupled, that he uttered an exclamation of anger and surprise.
“What is it?” cried Ned.
Tom held out a piece of cork. It had been stuffed into the pipe in such a way that for a time enough oil would pass to keep the motors running, but the cork would gradually swell and eventually would completely clog the pipe, shutting off all oil.
Without oil an engine will soon heat up, until, because of friction, the bearings, slide rods, pistons and cylinder walls may become red-hot. When that occurs the engine naturally stops. And when the engine of an aeroplane stops the plane falls. It is not like a dirigible that can sustain itself.
“Dirty work!” bitterly murmured Tom, as he worked with all possible speed to replace the pipe, for the secondary oil supply was fast failing. The plane was losing speed rapidly.
“Somebody must have got in, put some sort of dope in Dolan’s food or water, and also clogged the pipes,” said Ned.
“Right!” snapped out Tom. “But we aren’t beaten yet!”
And they were not. By hard work the young inventor got the other oil line cleaned, and then the Osprey at once picked up speed. However, much valuable time had been lost, and Tom was anxious lest the motors might have been permanently damaged by running without sufficient oil.