Advisory Circular (AC) No. 500-011 Issue 1 - Appendix A

Aircraft Carrying External Loads

1. The maximum size and weight of the external load, as well as limitations on the positioning of the load, must be determined. The effect of the asymmetric load must be addressed when the load is carried on one side of the aircraft. The maximum weight that may be so carried may be limited by aileron authority available to keep the wings level during takeoff. This applies particularly when a dense load, such as lumber, is carried.

2. For seaplanes, the load must be positioned in order that it will not catch and retain a significant volume of water during takeoff and landing.

3. A load may either be secured directly to the seaplane float struts or special provisions (e.g., boat rack) may be made for the carriage of external loads. Essentially, a repeatable means of securing the load to the aircraft must be determined. The load must be tightly restrained and held immobile. An external load may not be attached in any way to the wing struts unless continued compliance with applicable structural requirements is shown.

4. A single failure of a tie-down strap, rope or fitting must not be hazardous. Stacked lumber must be fastened together to form a unit such that no single piece(s) may come loose from the stack.

5. Emergency entry to or egress from the aircraft must not be unduly impeded by carriage of the external load, particularly in the takeoff and landing configurations. Any special procedures required or alternate egress routes must be clearly marked on the aircraft and these must be readily visible to persons attempting to leave the aircraft.

6. It must be shown that the position of the external load does not adversely affect the following:

(a) the travel of the flight controls;
 

(b) the operation of the undercarriage or flaps;
 

(c) the airflow in the vicinity of the pilot or static air sources;
 

(d) the propeller or rotor thrust; and
 

(e) the airflow in the vicinity of any air intake or exhaust port.

7. Performance - When a boat or canoe is carried as an external load on an aeroplane, the performance requirements of this AC apply, except that takeoff, climb, and landing performance need not be addressed provided that the certified maximum takeoff weight is reduced by twice the weight of the external load. Where the basic approved maximum weight is 3000 lb and the boat weight 100 lb, the maximum approved takeoff weight, including the boat, would be 3000 lb - 2 x 100 lb = 2800 lb.

8. Carriage Of Passengers - Up to 4 passengers may be transported in an aircraft carrying boats or canoes as external loads if the aeroplane has not been used for operations with loads exceeding certified maximum takeoff weight in accordance with this AC in accordance with the following:

(a) the gross takeoff weight reduction, detailed in paragraph 7 above, is specified as a limitation or compliance with the climb requirements of the basis of certification has been demonstrated;
 

(b) the aircraft is operated by day VFR only;
 

(c) the aircraft is operated within an approved flight envelope wherein acceptable flying qualities have been demonstrated;
 

(d) emergency egress from the passenger compartment is not unduly impeded by a boat or other externally mounted cargo. There must be clearly marked escape routes, and the passengers must be briefed before each takeoff if alternate escape routes are required; and
 

(e) placard requirements of paragraph 5.28(c)(6) of this AC are met.

9. An applicant must conduct flight tests of the proposed configuration and provide a flight manual supplement in accordance with this AC to obtain an approval.

10. The following limitations are suggested for aeroplanes carrying external loads except as otherwise determined by the approval process:

(a) maximum speed 100 kt;
 

(b) maximum bank angle 30°;
 

(c) ay VFR operations only;
 

(d) intentional spinning prohibited;
 

(e) intentional side-slipping prohibited; and
 

(f) boats and canoes are to be carried partially inverted, stern forward.

11. Past Approvals. STCs have been issued for a number of boat and canoe racks, particularly for the DHC-2 and DHC-3 aircraft. The status of these approvals has not changed, and they remain valid. A number of Canadian-registered aircraft have been granted LSTCs or one-off modification approvals for the carriage of external loads, and these approvals also remain valid. Additional LSTCs for aircraft previously cleared for the carriage of external loads may be possible without further Transport Canada Civil Aviation (TCCA) flight tests if the proposal is structurally acceptable and the applicant submits an appropriate flight test report and flight or operating manual supplement in accordance with this AC. TCCA flight testing may be required if one or more of the limitations noted in paragraph 10 are not adhered to.

Previous approvals include the following: