Recommends Aural Warning, Contrasting Color Bands On Indicator

In response to a July 2003 accident, on Thursday the National Transportation Safety Board issued three recommendations to the Federal Aviation Administration, addressing the Board's concerns with runway trim on Cessna Citation 525 model aircraft.

"On July 22, 2003, about 1015 Pacific daylight time, a Cessna Citation 525, N996JR, was ditched in the waters of Penn Cove, Coupeville, Washington, following a loss of elevator trim control that resulted in an uncommanded nose-down pitch attitude," the NTSB writes. "... According to the pilot’s postaccident statement, he configured the airplane’s autopilot for a climb to flight level 330, (33,000 feet) at an indicated airspeed of 200 knots, and a climb power setting shortly after departing Victoria International Airport about 0950.

"However, after climbing through 14,000 feet mean sea level, the pilot noticed a decrease in the airplane’s rate of climb. In response, he pressed the autopilot/trim disengage switch on the control yoke, which disconnected the autopilot. The pilot indicated that the airplane’s nose immediately pitched down to an attitude approximately 10º below the horizon and that "within seconds it was apparent that level flight was not possible" as he pulled back on the control yoke."

The NTSB adds the pilot took several measures to counteract the problem, then noticed the elevator trim indicator was in fill nose-down position. Despite efforts by both the pilot and passenger, seated in the copilot's seat, to hold the yoke back and attempt to move the trim wheel, it was apparent level flight could not be maintained.

"Despite the nose-down force on the control column, the pilot was able to maneuver the airplane to the vicinity of Whidbey Island, Washington, and attempted to land the airplane at a nearby airport," the NTSB says. "After reaching the island, however, the pilot determined he could not safely land the airplane on a runway and elected to land on the water at Penn Cove. He indicated that he extended the flaps to a landing position and, with the landing gear retracted, ditched the airplane into the water, coming to rest approximately 300 yards from shore."

Postaccident examination of the pitch control system found the autopilot trim down (K6) relay failed in the closed, or power on, position, according to the NTSB... resulting in power being continuously applied to the trim motor.

In such a condition, the autopilot/trim disconnect switch -- which the pilot did press -- would not have cured the problem; the only way to stop the motor from operating would have been to pull the pitch trim circuit breaker -- one of over 60 identical breaker switches on the panel.

The NTSB notes Cessna has since corrected the relay problem, in response to an FAA Airworthiness Directive; furthermore, all Citation 525s come with an "AP OUT OF TRIM" warning light above the altimeter to alert the pilot to such a runaway trim condition.

However, the Board believes an aural indicator is also called for, as well as other measures outlined below... to better call the pilot's attention to a potentially hazardous situation, and make it easier for them to take corrective action:

• Require Cessna to modify the Citation 525 to incorporate an aural trim-in-motion warning and the addition of contrasting color bands on the pitch trim wheel to provide the pilot with more timely recognition of a trim runaway condition before control forces become unmanageable. (A-07-52)
• Require Cessna to perform analysis and conduct a test to demonstrate that the maximum control forces in a Cessna Citation 525 meet the certification requirements of 14 Code of Federal Regulations Part 23 during a pitch trim runaway condition. The analysis and test should comply with the pilot-recognition time requirements provided in Advisory Circular 23-8, "Flight Test Guide for Certification of Part 23 Airplanes." If, after accomplishing the analysis and test, Cessna is unable to demonstrate that the Citation 525 meets the certification requirements, require Cessna to take corrective action so that the airplane does meet certification requirements. (A-07-53)
• Require Cessna to replace the pitch trim circuit breaker on the Citation 525 with a collared circuit breaker to aid the pilot in quickly identifying it if necessary. (A-07-54)

FMI: Read The NTSB's Full Recommendations