Chapter 4 - Preventative Measures and Deicing Procedures

Ground Deicing/Anti-Icing With Main Engines and/or APU Running

49.  A number of aircraft and engine manufacturers have published information on the advisability of deicing/anti-icing with the main engines running, and when permitted, there are procedures to be followed in order to protect the engines.

50.  Experience shows that problems can be minimized if precautions are taken to limit the ingestion of deicing/anti-icing fluid by the engines. The following procedures, which must be adapted to the specific aircraft type, were developed to protect the aircraft during deicing/anti-icing with the main engines running:

  • Operate as few engines as possible during the deicing process;
  • Operate at the lowest practicable power setting;
  • If possible select air conditioning 'OFF';
  • Avoid spraying fluid directly into the engine, APU, and air conditioning system intakes;
  • Avoid a large run-off of fluid from adjacent surfaces into the intakes, e.g., from a vertical stabilizer into a tail-mounted engine or APU;
  • Minimize the generation of spray in the vicinity of the intakes;
  • Configure the aircraft in accordance with Manufacturers specifications.

51.  Particular care should be exercised for the APU inlet because fluid ingestion could cause an APU runaway condition, flameout or, in an extreme case, an APU rotor burst which often results in a fire.

52.  More information can be found in the current CBAAC: "Ground Deicing/Anti-Icing Of Aircraft With The Main Engines Running" from the following website: https://tc.canada.ca/en/aviation/reference-centre/commercial-business-aviation-advisory-circulars/commercial-business-aviation-advisory-circular-cbaac-no-0072r.