Fatigue, Shift Handover and a Missed Torque Value
You are a B1 engineer on the night shift (22:00–06:00) at a line station. You have already worked 5 consecutive nights, each 10 hours, and this is your 6th. At 03:30 you are asked to complete a flap track lubrication and a landing gear actuator bolt replacement before the 06:15 departure. The previous shift handed over a job card where the torque value for the actuator bolt is illegible and the 'witness' signature is missing. You are tired, the hangar is poorly lit, and the supervisor is pressing for completion. You recall that the torque figure is 'around 40–50 Nm' but cannot find the maintenance manual page quickly.
1. Identify the human factors (dirty dozen) at play and explain how each could lead to an error.
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Relevant 'Dirty Dozen' factors:
- Fatigue - 6th consecutive 10-hour night shift; reduced vigilance, slower recall, higher risk of omission.
- Pressure - commercial departure deadline pushing you to skip verification.
- Lack of resources - illegible job card, poor lighting, manual not readily available.
- Lack of communication / handover - missing witness signature and unclear torque value from previous shift.
- Complacency / assumption - recalling '40–50 Nm' from memory rather than verifying.
- Distraction / stress - multiple tasks competing for attention.
Each of these independently raises the probability of an incorrect torque (under- or over-torque), which on a flight-control/landing-gear component could cause loss of fastener integrity.
2. What should you do about the illegible torque value and missing witness signature?
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Do not proceed on memory. Correct actions:
- Stop the task and obtain the current, approved maintenance manual (AMM) procedure and torque value from the controlled documentation system.
- Verify the part number and bolt specification against the illustrated parts catalogue to ensure the correct torque table applies.
- Raise a discrepancy on the handover - the previous shift's incomplete record must be corrected through the proper channel, not simply overwritten.
- Obtain a witness for the torque application and signature as required by the task card.
- Record the actual torque value, tool used (calibrated torque wrench with current calibration sticker), and your signature in the job card.
If you cannot resolve the documentation, escalate to the supervisor before touching the aircraft.
3. The supervisor insists you 'just finish it' to meet the departure. How should you respond, and what does CAR-66 require of you?
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You must decline to certify work you cannot verify. CAR-66 certifying staff are personally responsible for the airworthiness statement they sign; commercial pressure is not a defence. Response:
- State clearly that you cannot certify without the approved torque value and a valid witness signature.
- Offer a realistic alternative: request a delay, obtain the manual, complete the task correctly, or hand over to a fresh shift.
- Document the pressure and the reason for the delay in the technical log/handover.
Signing an unverified release would be a false certification, a breach of CAR-66 privileges, and a safety risk. Fatigue reporting and refusal to certify under pressure are protected behaviours under a just culture.