SEATTLE (AP) _ Suspicious damage was found to the wiring of up to 10 Boeing 737 jetliners undergoing final assembly, the company said Thursday.
Boeing has since increased security at its plant in the southern Seattle suburb of Renton.
Company spokeswoman Sandy Angers said Boeing discovered seven incidents of wire damage that are ``not common in the normal course of manufacturing.'' The company now also considers several earlier incidents suspicious.
Angers did not give details of the damage, but KIRO-TV in Seattle reported that the wires were cut, citing anonymous sources.
Each aircraft showed one instance of damage, but the damage was found in different places in each plane, Angers said.
The company notified the Federal Aviation Administration of the damage earlier this week, the same day the FAA was contacted by a whistleblower on the plant floor, FAA spokesman Allen Kenitzer said.
Kenitzer said the FAA referred the case to the FBI, which is considering an investigation because tampering with an aircraft is a federal crime.
Cases of employees intentionally damaging airplanes are rare, Kenitzer said. The last incident was reported in Seattle in 1990.
Boeing and FAA officials said the damage was easily detected when the airplane's systems were checked. Kenitzer said it would be highly unlikely for that type of damage to go undetected.