N143EM

On July 12, 2023, about 1400 eastern daylight time, a McDonnell Douglas A-4K, N143EM, was substantially damaged when it was involved in an accident at Cherry Point Marine Corps Air Station (Cunningham Field) Airport (NKT), Cherry Point, North Carolina. The commercial pilot sustained serious injuries. The airplane was operated as a Title 49 of the United States Code public aircraft.

The airplane was a light attack airplane formerly owned and operated by the Royal New Zealand Air Force. This variant of the A-4 was equipped with both a tailhook and a drag chute. The drag chute was added for additional assistance in slowing the airplane after landing or during an aborted takeoff, as the brakes lacked anti-skid capability.

According to the pilot, there were no irregularities or other anomalies discovered while briefing for the flight about 40 minutes before takeoff. The most recent maintenance documentation was for the installation of a heads-up display (HUD). The walk-around and preflight inspection were normal. All panels were opened, which allowed the pilot to inspect some of the internal components and systems including hydraulic pressures, hoses, and connections, and flight control actuation systems.

The pilot reported that all start-up and ground operations were normal, and none of the flight control checks revealed any anomalies. The wing flaps were set to 25° (half-flaps). The horizontal stabilizer trim and manual trim override were set appropriately and checked, with the trim actuator operationally tested and set on the rudder, ailerons, and elevator. There were no abnormalities discovered prior to or during the taxi or checks and after verifying the systems and gauges. A pilot in an adjacent airplane observed the accident airplane’s configuration before takeoff and did not observe any anomalies.

The reported weather conditions at NKT at 1356 included wind from 220° magnetic at 6 kts gusting to 15 kts. Special weather observations issued at 1346 and at 1411 reported winds from 270° magnetic at 7 kts, and 310° at 16 kts gusting to 24 kts, respectively.

Runway 5L was 8,491 ft-long. The runway was equipped with E-28 arresting gear 2,438 ft from the departure end; however, the arresting gear was unavailable at the time of the accident. Runway 23L was 8,188 ft long and also equipped with E-28 arresting gear 1,500 ft from the departure end of the runway. Runway 32R, the longest runway at NKT, was 8,979 ft long, and equipped with E-28 arresting gear 1,500 ft from the departure end.

The pilot reported that the takeoff roll was smooth with no abnormalities. The engine was making sufficient power and there were no warnings or cautions illuminated. As the airplane approached 145 kts, the pilot neutralized the control stick, and he could feel the nose strut extend; however, the nose landing gear remained firmly on the runway and there was no rotation. The pilot reported that he brought the control stick full aft and applied nose-up trim, but as the airplane passed 156 knots it remained on the runway without any rotation. Upon realizing that insufficient runway remained on which to take off, the pilot chose to eject. The pilot sustained serious injuries during the ejection and parachute landing.

The airplane departed the paved runway surface and traveled an additional 3,000 ft through the runway overrun area, impacting several runway/threshold lights, before coming to rest as fire enveloped the airplane. The airplane sustained substantial impact and thermal damage.

During recovery, the horizontal stabilizer pitch trim was found at 0°. The normal takeoff setting was between 6° and 8° nose up, which was confirmed before takeoff by ground maintenance personnel, the flight lead, and the pilot. Additionally, the flaps were found in the up (retracted) position. The normal takeoff flap setting was 25° (half-flaps); witnesses reported the flaps were down before the takeoff.

Examination of the horizontal stabilizer actuator limit switches and wiring revealed no anomalies. During operational testing, the horizontal stabilizer trim traveled nose-up and nose-down as directed with no irregularities observed. The trim switch and manual override stab switches were verified electrically neutral and were not stuck in the up or down position. According to the operator, a runaway nose-down trim during the takeoff roll was a known anomaly in the accident airplane make and model, and several incidents had occurred in US Navy and US Marine Corps fleet history. A runaway nose-down trim could be either mechanical or electrical in nature.

Further examination of the airplane revealed that the front left throttle quadrant air-to-air refueling store control head cannon plug was loose. The cannon plug was resting against the horizontal stab manual override push-pull rodend in a way that could limit operation. The cannon plug also showed evidence of severe chafing consistent with contact with the push-pull rod end.

According to the airplane’s takeoff performance chart, with a reported weight of 21,500 lbs, 6-kt tailwind, temperature of 32°C, and a barometric pressure of 30.02 in/hg, the airplane’s takeoff ground roll would be about 4,800 ft. According to the airplane operating handbook, page 5-4, aborting a takeoff, section 5.18:

There are many circumstances that may require aborting a takeoff. Some examples are as follows:

· Less than normal ERP/EGT/RPM

· Fire warning light

· Runaway nosedown trim

· Slower than normal acceleration

· Smoke in the cockpit

· Blown tire

· Loss of canopy

· Hazard on the runway

· Loss of oil pressure

· Dragging brake

· Uncommanded swerving

The decision to abort or continue the takeoff must be based on the nature of the malfunction, aircraft speed, wind component, runway remaining, arrest facilities, and whether or not the aircraft can become airborne prior to leaving the runway. A takeoff abort shall be accomplished by use of arrestor gear when available, unless it is certain the aircraft will be stopped or slowed to taxi speed by normal braking on the runway remaining. If there is no arrestor gear, then the decision to abort must be made prior to exceeding the takeoff refusal speed.

The procedure for a runaway nose-down trim scenario included aborting the takeoff if below refusal speed (108 kts). Above the refusal speed, the pilot should select flaps up, manual trim override nose up, jettison external stores, and deploy the ram air turbine. (See figure 1.)

Figure 1. Runaway nose down trim checklist memory items