Overview
On a scheduled night instrument flight rules flight, a de Havilland DHC8-311 (registration C-FACF, serial number 259) operated by Jazz Air Inc. as Flight JZA7956 departed from Runway 06L at Toronto/Lester B. Pearson International Airport (LBPIA) at 1950 eastern standard time, bound for Windsor Locks, Connecticut (KBDL). During the takeoff run, a three-foot piece of the wing leading edge, with the de-ice boot attached, separated from the left wing. The flight crew detected a vibration on the flight controls during initial climb and elected to return to Toronto. Air traffic control received a report of debris on Runway 06L, and the piece was retrieved. The aircraft landed without further incident on Runway 06L, with emergency response vehicles on standby. Examination of the leading-edge section revealed that the 14 screws securing it to the bottom of the wing were missing.
History of the Flight
The flight crew arrived from Cleveland, Ohio, at 1826 eastern standard time in a DHC8-100 and planned to depart at 1925. An earlier flight to Windsor Locks had been cancelled, and its passengers were transferred to Flight 7956. The increased passenger load necessitated a change to a larger aircraft, a DHC8-311. This required the flight crew to pass through U.S. Customs and Immigration, which was time-consuming. The captain checked paperwork including weather, flight plan, and maintenance records, while the first officer completed a walk-around inspection.
Maintenance Events
Task 3010/08, a maintenance task, was performed by several Aircraft Maintenance Engineers (AMEs). AME 1 picked the task to gain experience. He felt rushed as the task extended beyond his shift. After installing screws on the top of the wing leading edge, sealant was applied by an apprentice AME and AME 2. AME 1 then attended to other work and forgot to install the bottom screws, handing over the accumulated screws to the apprentice. His verbal handover to the crew chief was informal, stating that heaters in the left wing and tail were functional, that AME 2 and the apprentice would finish the right wing, and that he had not signed the task as complete.
The apprentice AME had not been assigned to the task but volunteered. He assisted with removing the leading edge and supported it during heater tests. He took initiative to seal the top of the wing but had no intention of sealing the bottom. The bottom screws were not set aside, providing no reminder. He did not check AME 1's work. After sealing the top, he moved to the right wing but was re-tasked to the ramp. He verbally informed the maintenance supervisor that work on the right wing was incomplete. Two hours later, at lunch, he told AME 3 that except for the right wing, everything was completed, without mentioning heater checks.
AME 2, the most experienced but newest to the company, volunteered to help obtain and apply sealant. He did not take ownership of the task and was not concerned about the bottom of the leading-edge panel. During significant periods, the three AMEs engaged in unrelated conversation.
The crew chief was reassigned daily based on seniority and had only eight months with the company. He received no training for the role and added supervisory duties to his own maintenance tasks. The maintenance supervisor issued the work package directly to the crew, undermining the crew chief's authority. The crew chief discussed task 3010/08 with AME 1 initially but did not directly supervise. He assumed sealant would be applied to both top and bottom of the leading edge. At shift end, realizing the task was not signed off, he signed it as complete, believing only the right wing leading-edge reinstallation remained.
AME 3 arrived on the night shift and found the task signed as complete but received a verbal briefing from the apprentice that the right wing portion was unfinished. He completed the leading-edge panel installation on the right wing but did not inspect heater operation or generate a task card for resealing. Before a taxi test, he conducted a walk-around but did not notice missing screws on the left wing. After the taxi test, he released the aircraft to service and parked it as a spare.
Company management amalgamated 11 independent maintenance tasks into a single OPT-3 task card, dropping the requirement for an inspector's signature. This change removed an opportunity to identify the missing screws before flight. There was no provision on the OPT-3 card to report deferred sealing, and no work card was generated for the unsealed leading edges. The company lacked a specific procedure for communicating work status at shift turnover.
Communication with Flight Crew
The flight crew's only maintenance information was a log book entry for work package #446, indicating an L-check—a routine 75-hour inspection. No specific focus areas were provided for pre-flight inspection.
Visual Cues
The unpainted brass-coloured screws are highly contrasted against black paint and pneumatic boots on the leading edges. Screw holes are countersunk with bare aluminum similar in appearance to unpainted screws. Unless specifically looking, the absence of screws was not obvious.
Findings
The investigation found that individuals working on the aircraft did not check their own work or that of others. There were no inspection procedures to ensure work completeness or proper recording of deferred tasks. Having extra personnel on site caused distraction and led to false assumptions about task completion. Additionally, no processes existed to ensure adequate communication between the maintenance manager, crew chief, and crew, or between shifts.