Challenger 300 engine short of takeoff power, Edinburgh 2017

BulletinEngine power loss

The short version

At Edinburgh the crew set takeoff power and the left engine fell short, with an L ENG EXCEEDANCE message on CAS. They stopped at very low speed, then tried again, and the same thing happened. A mechanic found that the bolt joining the left engine's compressor variable geometry actuator to its connecting rod was missing. It had been fitted incorrectly when the engine was serviced at a shop in the Netherlands a month earlier.

What happened

  1. Takeoff from Edinburgh for Warsaw. As takeoff power is set, the left engine does not reach the set power. The crew see L ENG EXCEEDANCE on CAS.

  2. The crew reject the takeoff at very low speed and leave the runway.

  3. The message goes out. The pilots decide to try again.

  4. On the second attempt power goes up very slowly. Left N1 rises much more slowly than right N1, the left engine again does not reach takeoff power, and L ENG EXCEEDANCE comes back. The crew leave the runway and taxi back to the stand.

  5. The next day a mechanic arrives from the operator. Engine data show many faults. Following Honeywell's guidance he adjusts the oil pressure, but on the ground run N1 still will not go above 56%.

  6. A second data download gives fault code MC-203, which points to the compressor variable geometry (CGV) actuator.

  7. With the actuator exposed, he finds no bolt at the joint between the CGV actuator and its connecting rod. The bolt is lying lower down in the engine. The nut is never found. A new bolt and nut are fitted, the engine run is good, and the aircraft is released to service.

The time is local.

The crew reported the event through the operator's safety management system and to its continuing airworthiness organisation. The operator then notified the Polish Civil Aviation Authority (ULC) and PKBWL.1

Why it happened

  1. The report found that the direct cause was the missing bolt and nut at the joint between the CGV actuator and the actuator connecting rod, because they had been fitted incorrectly.1

  2. The operator's safety department traced the history. A month before the event the left engine was removed at the operator's maintenance organisation and sent for service to an outside shop in the Netherlands. During that service the shop replaced parts of the actuator mounting bracket, including this bolt and nut, and fitted them incorrectly. Back in Poland, the operator's mechanics refitted the engine. They could not see the fault, because these parts sit inside the engine where they are not visible. The investigation ruled out mechanical damage to the bolt.

  3. The shop ran its own investigation. The report lists its contributing factors: no staff dedicated to specific tasks during the engine service, with the same people doing several other jobs at the same time; service paperwork too general, without the details of the work on the shop's internal task card; not enough qualified staff; work handed over between shifts; and work stopped and restarted because materials and spare parts were missing.

PKBWL made no safety recommendations. The operator filed a further occurrence report with the root cause to ULC, PKBWL, EASA and the engine shop.1

What a crew can take from it

  1. An engine that lags during thrust set is easiest to deal with at low speed. This crew saw the left engine fall short and stopped at very low speed, when stopping is easy. Watch both N1 needles as they come up, as well as the target. A split that keeps growing is a reason to stop before the speed builds.

  2. A message that goes out has not fixed anything. The exceedance message went out after the first stop, and the second attempt gave the same result. On the second attempt the crew added power very slowly, and the left N1 again rose much more slowly than the right. A message that clears does not tell you why the engine fell short. Before another attempt, check what your operator procedures and maintenance require after an engine exceedance.

  3. Read the recent maintenance history. This engine had just come back from a shop visit. The fault was inside the engine, out of sight of the people who refitted it and of the crew on the walkaround. A recent engine change or shop visit in the tech log is a reason to watch the first takeoffs and engine runs more closely.

Study it on the course

Sources

  1. Państwowa Komisja Badania Wypadków Lotniczych (PKBWL, State Commission on Aircraft Accidents Investigation), Poland. Informacja o zdarzeniu (occurrence information) 2009/17, Bombardier Challenger 300, EGPH, 30 July 2017. Investigation closed 18 September 2018. In Polish.
  2. PKBWL, occurrence register, entry 2017/2009.
  3. Aviation Safety Network, occurrence 312832.

Last updated 22 October 2026

For study only. Always use the approved AFM, QRH and operator procedures.