EGT exceedance on the go-around: airworthiness versus the schedule
On a go-around at Auckland from about 400 ft because the preceding aircraft was slow to vacate, the thrust levers were moved rapidly from idle to TOGA. During the go-around the ENG 1 EGT peaked at 906 °C and stayed between 875 °C and 890 °C for roughly 25 s before stabilising at 845 °C in the climb. The engine limits are 900 °C for 5 s maximum and 870 °C maximum continuous. On the ground the FADEC fault log shows an EGT exceedance and the maintenance computer flags an inspection. You have been on duty 11 h 20 min. The next sector departs in 50 minutes with 140 passengers, and the station engineer says 'it's probably just a sensor, we can look at it tonight'.
1. Is this an exceedance, and how would you classify it?
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Yes, on both magnitude and duration.
The limit structure matters more than the peak figure:
- 900 °C is permitted for no more than 5 s; the peak was 906 °C, so the limit was exceeded in magnitude;
- the temperature then sat between 875 and 890 °C for about 25 s, while maximum continuous is 870 °C - so the engine also spent roughly half a minute above its continuous limit.
An exceedance is assessed on peak and time together, not on either alone. Time above the limit is what accumulates damage in the turbine: creep, oxidation of blades and nozzle guide vanes, and loss of EGT margin.
The FADEC log confirming the event is data, not an opinion - it records what the engine saw. The maintenance manual exceedance chart then translates peak and duration into required action. The classification sits somewhere between 'log entry only' and 'hot-section inspection', and only the chart plus the engineer can settle it. What it is not is a no-action event, and 'probably just a sensor' is not a diagnosis when those same sensors govern every takeoff the aircraft makes.
2. What are your actions and documentation before the next departure, and who makes the decision?
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- Technical log entry with peak EGT (906 °C), time above 870 °C (~25 s), the phase of flight (go-around, TOGA), and the OAT and altitude at the time. It must be legible to an engineer who was not there.
- Notify maintenance control and let them apply the engine manual exceedance chart. The licensed engineer or approved maintenance organisation releases the aircraft; the captain's signature accepts a serviceable aircraft, it does not make one serviceable.
- Occurrence/defect report per the operator's system and, where the criteria are met, CAA notification. The exceedance may itself be reportable and the reason for the go-around is worth capturing.
- Do not depart until a release is issued. 140 passengers and a 50-minute turnaround are commercial pressure, not airworthiness data. If the inspection cannot be completed before the next sector, the sector does not go. Make that call early so the operator can replan rather than discovering it at the gate.
If the engineer works the chart, finds a log-entry-only outcome and signs it off, you can go - with the write-up in the log and the reduced EGT margin understood and briefed for the next hot-day takeoff.
3. What human factors contributed, and what would reduce the chance of a repeat?
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- Surprise and time pressure. A go-around at 400 ft is a sudden high-workload event; the natural response is a large, fast thrust lever movement.
- Fatigue. After 11 h 20 min of duty, tolerance for a sudden change drops and the temptation rises to accept the easy explanation the engineer offered.
- Authority gradient and commercial pressure. The station engineer's casual dismissal and the 140 passengers both push towards departing. The crew has to hold the line without becoming obstructive.
- Low-power to high-power transition. After a long period at idle the engine is cold-soaked and working from the bottom of its acceleration schedule; a smoother, slightly slower lever movement, or advancing to an intermediate setting first, reduces the EGT overshoot.
Prevention: brief the go-around before every approach, including thrust handling; make thrust lever movements deliberate from low power; plan engineering time at the destination instead of a tight turnaround after a late arrival; and treat every exceedance as real until an engineer says otherwise with the chart in hand.