Worldwide there are 174 MD-11s affected by Thursday's directive RELATED VIDEO CNN's Carl Rochelle explains the reasons behind the ordered inspections Windows Media 28K 80K

WASHINGTON (CNN) -- The Federal Aviation Administration Thursday ordered airlines to inspect all U.S.-registered MD- 11 airplanes for cockpit wiring problems after signs of heat damage and electrical arcing were found in the wreckage of Swissair Flight 111, which crashed last September off the coast of Nova Scotia.

Canadian authorities still have not determined the cause of the crash but have discovered heat damage and signs of arcing in the cockpit ceiling and the avionics circuit bay. Subsequent inspections found similar problems in other MD-11 aircraft.

The FAA order requires airlines to inspect the planes and make any necessary repairs within 60 days. The order affects 174 MD-11s worldwide, 65 of which are flown by U.S. carriers including Delta and American. The inspections should cost about $720 per plane, a total of $46,800.

The order says examination of several MD-11 jetliners had "revealed chafed, cracked, broken and cut electrical and bonding wires" in the forward area of the planes. The order said "these conditions, if not corrected, could result in electrical arcing of wiring and consequent fire and/or smoke in the cockpit of the cabin."

The Swissair crash occurred September 2 about an hour after the plane took off from JFK International Airport in New York bound for Geneva, Switzerland. All 215 passengers and 14 crew members were killed in the crash.

About two weeks ago, the National Transportation Safety Board wrote a letter to FAA Administrator Jane Garvey urging her to order airlines to inspect the MD-11s. The FAA responded at the time that it was already drafting an order and expected to take action shortly.

In December, the FAA also ordered airlines to inspect doors after the Swissair investigation revealed wire chafing problems. Swissair also has conducted voluntary inspections of its MD-11 airplanes, but those inspections have not uncovered serious discrepancies, the NTSB said.

There may be more action on the MD-11 down the road. The FAA is describing Thursday's order as an interim action, until it can determine the full extent of any potential wiring problems.