Rat poop may be the immediate health risk, but gnawing on wires is even more dangerous.

We found this out the expensive way a couple of times in Kansas, when rats, seeking warmth, entered the car’s engine and decided to go for a chomp.

It’s happened twice.

Bloomberg reports that rodent droppings “too numerous to count” were found by U.S. health inspectors near a Delta Air Lines Inc. (DAL) jet’s galley where food and drink are stored.

The excrement and mammalian urine turned up in inspections at a Delta hangar in Atlanta, the Food and Drug Administration said in an April 13 letter to the airline.

Delta’s response to the agency didn’t include steps to prevent a recurrence, which is “likely” unless such measures are taken, the FDA said.

The FDA said the inspections took place from Jan. 26 through Feb. 2. Rodent excrement was discovered above the right and left forward galleys and mammalian urine was detected in six areas on ceiling panels over a galley, according to the FDA.

Chad Artimovich, president of Atlanta Wildlife Solutions LLC, a pest-control company, said,

“Once it gets in there and gets established, there’s no reason to leave. The real concern is if a rat started chewing on wires. Almost every house I go into where there are rats, they’ve chewed on wood and wiring and ornaments. Their teeth are harder than iron and they have to keep them gnawed down.”