Flight Details
On February 16, 2012, at about 1308 local time, Everts Air Cargo flight 1291, an Embraer EMB-120 (registration N1110J), was descending into Iliamna Airport (KILI) in Iliamna, Alaska. The flight operated under 14 CFR Part 121 Supplemental as a cargo-only flight originating from Anchorage, Alaska (KANC). Two crewmembers were on board; there were no injuries, but the airplane sustained substantial damage.
Incident Description
The captain reported an uneventful flight from Anchorage. During the descent, at approximately 250 knots indicated airspeed with the autopilot engaged, the airplane pitched nose-down to about 20 degrees while the captain's hands were on the controls. The captain disconnected the autopilot, adjusted the pitch trim, and pulled back on the control column to recover. The flight crew declared an emergency and slowed the airplane to about 200 knots.
About 5 to 10 miles from the airport, while hand-flying a slow left turn at 3,000 feet mean sea level, the airplane pitched down a second time. The captain recovered and aligned the aircraft for a 5-mile final approach to runway 35. He elected to perform a high-speed, flaps-up landing, which was completed uneventfully on runway 35.
Post-Flight Inspection
A post-flight inspection revealed that the left elevator was bent at the mid-span trim tab, had partially detached from the aircraft, and was missing two attachment bolts.
Maintenance History
A review of the airplane's maintenance history showed that during an "A" check, a dent was noted in the left elevator, and the elevator was subsequently removed. The maintenance team did not follow the Embraer EMB-120 maintenance manual procedure for removal of the left elevator. During non-routine maintenance procedures, cotter pin safeties that had been removed from castellated nuts on the two outboard vertical hinge bolts of the left elevator were not reinstalled. The removal of these two bolts is not part of the EMB-120 maintenance manual procedure for left elevator removal. Additionally, the maintenance team did not document the non-routine procedure used.
The Required Inspection Items (RII) inspector inspected the elevator installation according to the manual procedures and was unaware of the undocumented non-routine maintenance. Consequently, the inspector did not examine the nuts that lacked the required cotter pins. The Federal Aviation Administration found that the maintenance teams involved were inexperienced in EMB-120 elevator removal and reinstallation procedures.