Maintenance matters

Flying Safety, Sept, 2004

Editor's Note: The following accounts are from actual mishaps. They have been screened to prevent the release of privileged information.

To continue the airframe specific theme, here is the first fighter version. I took a look at the F-16, since it is the most numerous and one of the busiest fighters we have.

Raise the Gear, No That's the Canopy

The F-16 gear checkout team was composed of maintenance technician-A (MTA), seated in the forward cockpit, MTB, standing on the left side of the aircraft reading the job guide, MTC, operating the hydraulic servicing cart, and MTD, seated in the aft cockpit. MTA and MTD were both working with the F-16 for the first time since being assigned to the team earlier in the week. Supervision for the landing gear team had not documented whether proper qualifications were met or training requirements satisfied for any team members. All technicians were on headset and able to communicate with each other. The team was to complete the basic landing gear operational checkout, which had been stopped the day before due to the discovery of a hydraulic reservoir leak, and the alternate extension system operational checkout. The team performed a Foreign Object Damage (FOD) check around the aircraft before beginning the checks, but failed to perform the aircraft safety procedures required by tech data. The team performed a brake bleed and leak check prior to continuing the basic operational check from the day before. The brake bleed and leak check and the basic operational check were uneventful.

The team then began the alternate extension system operational checkout. The procedures call for the forward cockpit alternate extension system to be checked before the aft cockpit system. The checkout for the forward cockpit was uneventful until step 29, which states: "29. (A) Position gear handle to up." (The (A) means technician A, seated in the front cockpit, should perform the step.) MTB directed MTD to raise the gear. At some undetermined time, prior to this moment, the canopy jettison handle safety pin was pulled and placed next to the handle. MTD pulled the canopy jettison handle, initiating the canopy jettison sequence. The canopy, doing just what it was designed to do, jettisoned, contacting and bending electrical conduits on the ceiling of the hangar. The canopy then fell onto the aircraft, damaging the spine, tail, left wing, and missile rail launcher before falling to the hangar floor and coming to rest nearest the forward edge of the left wingtip. The MTB and MTC shut down the hydraulic servicing cart and disconnected the power while MTA and MTD egressed the aircraft. The team then egressed the hangar.

The main causes of this mishap were failed supervision, failure of the team to follow tech data and lack of training. How qualified are your people, and are they using tech data? Is your supervision setting people up to fail by not ensuring tech data is followed?

Stuck Throttle

The mishap pilot (MP) was on a continuation training sortie, and on recovery the MP noticed an equipment hot caution light. The MP attempted to reduce power, but the throttle would not physically move more than an inch or two aft of the military position. The MP notified the flight lead of a stuck throttle and equipment hot light. The flight lead passed the lead to the MP, went to a chase position, and directed the MP to point to high key at the home base. At this point, the mishap aircraft (MA) had approximately 5000 pounds of fuel. The MP analyzed the situation en route to high key and he had minimum engine rpm (88 percent), fuel flow was 6900-8800 pounds, and the FTIT was normal. The MP could maintain approximately 300 KIAS with the throttle in its stuck position and the speedbrakes in override. The MP then declared an IFE. After much work and coordination for the jettison of stores and the decision to run the engine out of fuel, the aircraft landed safely and took the approach end arresting cable.

Maintenance took over and found the aircraft engine had been installed six months prior to the mishap. The aircraft had over 150 uneventful sorties since the engine was installed, and all inspections were completed IAW tech order guidance since the engine was installed. After MX removed the engine from the aircraft, they discovered a 1/4-inch engine bolt stuck in the main fuel control (MFC), restricting the throttle from full movement. After a thorough investigation of the engine, there was a bolt and nut missing from bolt position number 45 on the "e" flange (aft of the fan and the beginning of the core) of the engine. The bolt stuck in the MFC was the same part number as the missing bolt on the "e" flange. The missing nut was never located. The key here is: Why did the nut come loose? No one knows, but maintenance must do all we can to prevent this potential loss of an aircraft.

Aircraft Attacks Tech Order or Vice-Versa

A maintenance team had completed the installation of the rudder integrated servoactuator and was beginning to perform the hydraulic system operational checks. Mishap Personnel 1 (MP1) and Mishap Personnel 2 (MP2) were on top of the aircraft, visually inspecting for evidence of leaks. MP1 placed the job guide on top of the aircraft prior to hydraulic power being applied. As Mishap Personnel 3 (MP3) applied hydraulic power, the aircraft abruptly shuddered (normal operation). When this movement occurred, the job guide fell from the backbone of the aircraft and slid down between the airframe and the left horizontal stabilizer as the surface was in motion. The stabilizer pinned the tech order against the airframe, and the stabilizer sustained delamination and tearing damage to its upper surface.