IAD01IA019

While climbing through 26,000 feet, the airplane began to pitch up and down at a fast rate. The captain took control of the airplane and leveled off. The airplane continued to pitch up and down, the autopilot was engaged, and the airplane stabilized. The airplane was slowed to 230 knots and the autopilot was turned off. The pitch oscillations began again. The crew declared an emergency and returned to Newark International Airport, Newark, New Jersey, and landed without incident. The left inboard elevator parallel engage solenoid shut off valve was replaced and no further discrepancies were noted with the system. Examination of the faulty valve revealed that a short was found when tested between coil 1 and coil 2. Disassembly of the unit revealed that hydraulic fluid was found underneath the case assembly and around the coil assembly. The examination also revealed that the orange colored lead to coil 1, and the brown colored lead to coil 2 had fused together through the insulation and caused the electrical short. It could not be determined as to how the hydraulic fluid entered the valve, or if the fluid contributed to the electrical short. At the time of this report, Boeing was in the process of establishing a components team to research the possibility of fluid contamination in these valves.

On November 25, 2000, at 0813 Eastern Standard Time, a McDonnell Douglas MD-11, N582FE, operated by Federal Express as flight 3015, was not damaged after experiencing pitch oscillations while climbing through 26,000 feet after takeoff from Newark International (EWR), Newark, New Jersey. The two certificated airline transport pilots were not injured. Visual meteorological conditions prevailed and an instrument flight rules flight plan was filed for the flight destined for Oakland, California. The scheduled cargo flight was conducted under 14 CFR Part 121.

According to Federal Express, the first officer was hand flying the airplane. At 26,000 feet, the airplane began to pitch up and down at a fast rate. The captain took control of the airplane and leveled off. The airplane continued to pitch up and down, and the autopilot was then engaged and the airplane stabilized. The airplane was slowed to 230 knots and the autopilot was turned off. The pitch oscillations began again. The crew declared an emergency, and returned to EWR, and landed without incident.

The crew remarked that while hand flying the airplane, the elevator pressure was similar to when the autopilot was engaged, and described it as a very heavy pressure. The autopilot remained engaged (auto pilot single alert) to 1,000 feet. The crew reported that there was very heavy pressure on the elevator during the landing.

According to Federal Express, a maintenance write-up on November 22, 2000, revealed that the elevator had locked up and the airplane had to be flown with stabilizer trim to change pitch angle.

Federal Express maintenance personnel at EWR examined the airplane. The number 1 flight control computer (FCC) was replaced, and the horizontal stabilizer jackscrews and chains were visually inspected and functionally tested. The number 1 and 2 FCC auto flight system (AFS) CAT3B return to service test (RTS) was performed and functionally tested okay. The electrical connectors on the left inboard actuator were replaced due to moisture contamination. Also, the right hand outboard elevator actuator shut off solenoid was replaced.

The airplane was then test flown. During the test flight, the oscillations were again encountered. The left inboard elevator parallel engage solenoid shut off valve was then replaced and no further discrepancies were noted with the system.

The valve was sent to the manufacturer for examination.

The valve was examined at Parker Aerospace, Irvine, California, on January 19, 2001. Present for the examination were representatives of Parker Aerospace and Federal Express. Examination of the valve revealed that it was intact, and was assembled in accordance to manufacturer standards. The unit had accrued a total of 13,467 hours. The unit was electrically tested, and a short was found when tested between coil 1 and coil 2. At that time, no further electrical or hydraulic testing was conducted due to the short. The unit was then disassembled. Examination of the unit revealed that moisture was found underneath the case assembly and around the coil assembly. The moisture appeared to be hydraulic fluid. The examination also revealed that the orange colored lead to coil 1, and the brown colored lead to coil 2 had fused together through the insulation and caused the electrical short.

It was not determined as to how the hydraulic fluid entered the valve, or if the fluid contributed to the electrical short.

According to a Boeing representative, the valve failure was not a common occurrence. At the time of this report, they were in the process of establishing a components team to research the possibility of fluid contamination in these valves.