Advisory Circular (AC)

Appendix A - Additional Technical Conditions for Aeroplanes used in Firefighting Role

A.1 Flight Characteristics

Satisfactory controllability and manoeuvrability shall be demonstrated during:

  1. Normal load dropping in all firefighting configurations.
  2. Accelerate stop with a full load.
  3. Accelerate stop with a partial load (if approval of partial filling of the tanks is requested).
  4. Emergency load jettison at V2 during take-off climb with an engine failure.
  5. Emergency load jettison at stall warning in the firefighting configuration.
  6. Emergency load jettison during a 45 degree bank turn in the firefighting configuration.
  7. Abnormal load jettison en route.
  8. Pushover to zero G with full load.
  9. Pull-up or wind-up turn to 2g with full load.
  10. Flight and landing with tank doors open (failure case).

A.2 Airspeed Limitations

Maximum firefighting speed should be not less than 1.5VS or VMCA+20 knots (whichever is greater) to provide an adequate manoeuvring speed envelope for the firefighting role.

A minimum recommended speed of 1.25VS or VMCA, whichever is greater, should be presented in the AFM to allow for gusts, turbulence and manoeuvring margin to the stall.

The following speeds should be established for abnormal procedures:

  1. Maximum load dropping speed.
  2. Maximum dropping speed for abnormal load release in the enroute phase of flight.
  3. Maximum operating speed with one or all of the load tank doors open.

A.3. Limit Manoeuvring Load Factors

  1. The complete aeroplane including the suppressant dropping installation must be designed to withstand the following symmetrical limit manoeuvre load factors. Pitching velocities appropriate to the corresponding pull-up and steady turn manoeuvres must be taken into account:
    1. The positive load factors for any speed up to the design dive speed may not be less than 3.0 g; and
    2. If wing flaps or other high-lift devices are intended for use during flight conditions additional to take-off, approach and landing, a positive manoeuvre load factor of 3.25g for all speeds up to the selected flap or high lift device design speed shall apply.
  2. Alternate Manoeuvring and Gust Conditions:

    In lieu of the manoeuvring load factors specified in (a) above, the applicant may use alternate manoeuvring and gust envelopes which have been shown to be appropriate and which, when associated with operating limitations will provide for safe operation of the aircraft.

    Any such proposed manoeuvring envelope should conservatively encompass specific manoeuvring occurrences peculiar to the fire-fighting activities. Likewise, the gust envelope should take into account the response of the aircraft to atmospheric turbulence of the maximum intensity likely to be encountered in the vicinity of a fully developed fire.

A.4 Weight and C.G.

The following must be considered:

  1. Maximum firefighting weight.
  2. Maximum fire suppressant tank load.
  3. Maximum fire suppressant tank capacity.

A.5 Fire Suppressant Tank loading Limitations

Consideration should be given to acceptable loading configurations, for example carriage of partial loads.

A.6 Markings and Placards

Each fire suppressant tank and associated equipment must be clearly marked as to its maximum allowable capacity, operation of controls and any associated limitations (for example, order of tank replenishment).

Suppressant filler openings must be marked at or near the filler indicating their respective tank.

Foam filler openings must be marked at or near the filler cover.

A.7 Procedures

Normal and abnormal procedures relating to the suppressant drop system and any other related system affected by the installation must be presented.

These may include but not necessarily limited to:

  1. Load tank doors fail to open.
  2. Load tank doors fail to close.
  3. Flight and landing with the load tank doors open.
  4. Normal and emergency load release.
  5. Loss of any related system (e.g., Hydraulic low pressure).
  6. Failure to transfer suppressant or additives from auxiliary tanks.

A.8 Occupancy

Occupancy is to be restricted to essential crew, including trainees, during firefighting operations, training, or any time a load is carried in the firefighting tank.

A.9 Maintenance Manual Supplement

A Maintenance Manual Supplement approved by Transport Canada may be required that describes additional systems system in detail and sets out the maintenance procedures and schedules for example, firefighting aircraft shall include:

  1. Inspection procedure for use of seawater/chemicals for fire suppression;
  2. Inspection procedure for converting to and from the fire fighting version; and,
  3. Any special preventive maintenance instructions to safeguard against corrosion and fatigue.

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