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Working Group

General Operating and Flight Rules Technical Committee (Part VI)

Final Report

External Loads Working Group 

Terms of Reference

The External Loads Working Group was charged with investigating the potential of extending or replacing CAR 703.25, with a regulation under Part VI, irrespective of the carriage of passengers and to make recommendations accordingly. The "Background" in the Terms of Reference identifies the problem as, ".the issue of the carriage of external loads on aircraft.." A more explicit definition of the problem evolved as the WG struggled with the issue.

The Problem

The WG members recognize the problem as applying to aircraft in the aeroplane and helicopter categories, and to private and commercial air operators.

The problem is - the carriage of external loads by air operators, with or without passengers onboard, without the approval to do so in a type certificate or supplemental type certificate (TC/STC). The problem became more clearly defined with the coming into force of CAR 703.25, "Except where carriage of an external load has been authorized in a type certificate or supplemental type certificate, no air operator shall operate an aircraft to carry an external load with passengers onboard." This regulation, while prohibiting passengers, does not prohibit unauthorized external loads when there are no passengers. Thus, the regulation is being misinterpreted as allowing external loads without passengers. Other regulations prevent this because the flight authority for an aircraft becomes invalid if an aircraft has not been certified to carry an external load.

The difficulty with external load operations that take place without TC/STC approval, is that they are done without the benefit of certain provisions that decrease the risks inherent in these types of operations. The TC/STC set out conditions that diminish those risks, thus providing for safer operations. The WG agreed that external load operations outside of the provisions of a TC/STC need conditions to offset the risks that are assumed in these activities. Additionally, these risks can be mitigated by regulation if the regulation concisely defines what external load operations are permitted without a TC/STC (applicability), sets out under what conditions they may take place, and is supported by the appropriate advisory material. Even under these circumstances, the carriage of passengers brought additional concerns. 

Interim Solution

As an interim solution, commercial air operators in 1997 were provided with an exemption to 703.25 that was renewed for 1998 and 1999. This exemption permits air operators to carry external loads with passengers, without an approval in a TC/STC, provided certain conditions apply. Implicit in the exemption is that Transport Canada recognizes the practice, and that it can be done safely with certain conditions in place to mitigate the risks. Note: The exemption is not applicable to private air operators or helicopters.

Helicopters

The WG reviewed the question of helicopter external loads in light of the terms of reference. Helicopter class B, C and D loads are external loads that are slung under the aircraft, can normally be jettisoned, and require helicopter pilots to 'fly the load' along with the helicopter or tow it along the ground. These external loads represent a complex challenge to both the aircraft and pilot beyond that encountered in fixed wing operations. There are no aeroplane configurations that sufficiently approximate the technical complexity involved in helicopter class B, C, and D load operations. The view of the WG is that these operations should continue to require the aircraft to have the appropriate TC/STC, and are therefore outside the scope of this WG. However, because helicopter class A loads are fixed and do not move during flight, they are included in this report.

Commercial/Private

WG Strategy

The WG elected to address the issue in two stages. In the first stage the WG identified the risks of conducting external load operations with no passengers, and determined measures that could be used to mitigate those risks. In the second stage, using the results obtained from the first stage, the WG identified what new concerns arise when passengers are carried during external load operations, and what additional mitigation was needed. The results follow.

The Risks

The following risks were identified for external load operations that occur without TC/STC approval:

  1. is the reduced flight envelope still acceptable; 
  2. altered flight characteristics; 
  3. means of attachment used to secure a load may fail; 
  4. potential for external loads to obstruct persons from exiting aircraft in an emergency; 
  5. inadequate recording of external load data for pilot information; 
  6. inadequate availability of external load data for pilot information; 
  7. structural damage to the aircraft; 
  8. disposition of the aircraft flight authority; and 
  9. unintended use of new external load regulations

RISKS / MITIGATING CONDITIONS

RISK 1

Is the reduced flight envelope still acceptable.

MITIGATION - NO PASSENGER

  • A proving flight is to be conducted for each load configuration or aircraft configuration change, that has not been the subject of a proving flight and for which data has been recorded and is available as set out in the "MITIGATION" for "RISK 5" and "RISK 6." 
  • In accordance with the "Proving Flight Checklist (Appendix A for aeroplane or Appendix B for helicopters)," the pilot is to determine that the performance and flight characteristics of the aircraft require no exceptional pilot alertness, knowledge, skill or strength. 
  • The proving flight is to be a separate flight and not to be combined with a transportation flight, it is to be conducted as close to the airport or aerodrome as is practicable, and the aircraft is to take off from and land at the same location. 
  • All records referred to in the "MITIGATION" for "RISK 5" are to be completed before the commencement of a transportation flight. 
    Crew members only onboard the aircraft during the proving flight. 
  • The minimum pilot experience, for the person conducting the proving flight, shall be 250 hours pilot in command time, with 25 hours pilot in command time on aircraft class and type. 

    NOTE 1: The purpose of a proving flight is to prove that the aircraft will perform acceptably within a subset of the original aircraft flight envelope parameters. While a proving flight does establish a subset of the flight envelope, it is not a test flight. Normally, a test flight is expected to explore and determine flight envelope limitations, and is performed by a qualified test pilot in a test flight environment (preflight engineering calculations, etc. available). Even so, the proving flight requires sufficient experience to adequately determine or define parameters such as speeds, angle of bank, climb rate, etc., and to recognize poor flight qualities at their initial onset. Thus, minimum pilot experience should be 250 hours pilot in command time with 25 hours pilot in command time on aircraft class and type.

ADDITIONAL MITIGATION - WITH PASSENGER

  • No additional mitigation needed.

RISK 2

Altered flight characteristics.

MITIGATION - NO PASSENGER

  • The aircraft is to be operated under DAY/VFR conditions only. 
  • The airflow in the vicinity of the pilot and static source and other air scoops or exhaust ports shall not be adversely affected by the presence of the external load or its securing system. 
  • The external load is to be mounted: in such fashion as to minimize the effect of the turbulence, generated as a result of the load, on the tail surfaces; far enough aft of the propeller to prevent interference with the airflow and possible cavitation; and in a manner that prevents significant amounts of water from being caught and retained. 
  • If a boat with a blunt stern is carried it must be mounted stern forward. 
  • Where a number of separate pieces are carried together (i.e., lumber, pipes), these pieces must be fastened together to prevent a single piece from coming loose. 
  • A means of monitoring the engine operating temperatures must be provided. 
  • The aircraft structure must be protected from chafing, dents or damage caused by vibration or shifting of the external load. 
  • The maximum bank angle not to exceed 30 degrees. 
  • The maximum operating speed is not to be more than 90% of the maximum demonstrated to be safe during the proving flight, and not to be less than 1.5 times the stall speed. 
  • Where a climb performance check, as specified in the "Proving Flight Check List", has not been successfully completed, the aircraft maximum gross weight aircraft shall be reduced by twice the amount of the weight of the external load. 
  • Where a climb performance check, as specified in the "Proving Flight Check List", has been successfully completed, the aircraft maximum gross weight need not be reduced. 

    NOTE 2: In the absence of a climb performance check, past Regulatory Guidelines favour a maximum certified take off weight (MCTOW) penalty equivalent to two times the weight of the external load; however, anecdotal evidence from industry indicates that a MCTOW penalty equivalent to the weight of the external load would be sufficient in non passenger carrying operations. The Working Group recommended that further evaluation of this requirement be undertaken by Transport Canada Civil Aviation.

ADDITIONAL MITIGATION - WITH PASSENGER

  • In addition to the mitigation factors outlined above, where a climb performance check, as specified in the "Proving Flight Check List", has been successfully completed, the aircraft maximum gross weight shall be reduced by an amount equal to the weight of the external load. 

RISK 3

Means of attachment used to secure a load may fail.

MITIGATION - NO PASSENGER

  • The load shall be located and attached to the aircraft in a manner that is both secure and repeatable, using three separate ropes, straps or other means such that failure of any single connection does not create a hazard.

ADDITIONAL MITIGATION - WITH PASSENGER

  • No additional mitigation is needed. 

RISK 4

Potential for external loads to obstruct persons from exiting aircraft in an emergency.

MITIGATION - NO PASSENGER

  • The load is to be located so as not to impede emergency egress from the aircraft. 
  • Any alternate escape route is to be identified and clearly marked. 

ADDITIONAL MITIGATION - WITH PASSENGER

  • Passenger briefings are to be mandatory. 
  • The air operator must emphasize any special egress procedures in the passenger pre-flight briefing and the alternate escape routes must be clearly marked. 

RISK 5

Inadequate recording of external load data for pilot information.

MITIGATION - NO PASSENGER

  • Private Aircraft - The pilot is to make an entry in the aircraft journey log stating the: date, time and location of the proving flight; pilot licence number of the pilot who conducted the proving flight; a definitive technical description of the external load configuration that was tested (the item - its orientation and location relative to the aircraft); the readily repeatable means of securing the load to the aircraft; and the operating limitations referred to in the "MITIGATION" for "RISKS 1, 2, 4, 7 and 9, using the following formula."

    "I have flown this aircraft and consider it safe to fly with (a definitive technical description of the external load configuration that was tested [the item, - its orientation and location relative to the aircraft]); externally mounted by (identify and detail the means of mounting the load) and operated in accordance with the limitations and procedures detailed in this aircraft journey log.

    Location_________________ Date_________ Time________

    Licence Number___________ Signed__________________    "
  • Commercial Air Operator - The company operations manual is to contain direction to flight crews concerning operations with external loads, including: a definitive technical description of the external load configuration that was tested (the item and its orientation relative to the aircraft); the position of the load on the aircraft; the readily repeatable means of securing the load to the aircraft; and the operating limitations referred to in the "MITIGATION" for "RISK 1, 2, 4, 7 and 9," using the following formula.

    "I have flown this aircraft and consider it safe to fly with (a definitive technical description of the external load configuration that was tested [the item, - its orientation and location relative to the aircraft]); externally mounted in accordance with (identify the document detailing the means of mounting the load) and operated in accordance with the limitations and procedures detailed in (identify the document).

    Location_________________ Date_________ Time________

    Licence Number___________ Signed__________________    "
  • The results of the proving flight, conducted in accordance with the "Proving Flight Checklist," are to be retained by the operator. 
  • Commercial air operator - Prior to an external load operation the chief pilot or his delegate is to train, authorize and certify the pilot accordingly, and maintain a record of the training, authorization, and certification in the training file for each pilot so trained.

ADDITIONAL MITIGATION - WITH PASSENGER

  • No additional mitigation is needed.

RISK 6

Availability of external load data for pilot information.

MITIGATION - NO PASSENGER

  • Advisory information to be developed and accompany the regulation, including training material for new pilots. 
  • The air operator and pilot, or in the case of a private aircraft, the pilot, is to review and consider all information that is required to be recorded in "RISK 5", and all advisory material pertinent to the external load to be carried, and exercise due diligence in its application.

ADDITIONAL MITIGATION - WITH PASSENGER

  • No additional mitigation is needed. 

RISK 7

Structural damage to the aircraft.

MITIGATION - NO PASSENGER

  • The aircraft is to have an otherwise valid flight authority. 
  • The external load operation shall not affect the structural integrity of the aircraft. 
  • The pilot is to check the aircraft at the attachment and location areas of the external load for damage after each landing. 

ADDITIONAL MITIGATION - WITH PASSENGER

  • The aircraft shall be limited to flight in nothing greater than light turbulence, 

    NOTE 3: The WG consensus is that in a "with passenger" operation, the level of concern is increased, and additional mitigation is indicated. The rationale is that the parameters of the reduced flight envelope (a subset of the flight envelope) could inadvertently be exceeded as a result of weather, turbulence, etc. Therefore, because the area outside of the subset flight envelope is not tested, additional mitigation is needed to better guard against an aircraft excursion outside the subset flight envelope.

RISK 8

Disposition of the aircraft flight authority.

MITIGATION - NO PASSENGER

  • A regulatory provision is required that will, provided the external load regulations are complied with, validate the aircraft flight authority during the external load operation.

ADDITIONAL MITIGATION - WITH PASSENGER

  • No further mitigation is needed. 

RISK 9

Unintended use of new external load regulations.

MITIGATION - NO PASSENGER

  • Except for securing the external load to an approved bracket or other approved device, the external load is not to be connected to any of the aircraft systems. 
    The purpose of the flight, excluding stops for fuel, crew rest, repairs, weather, emergencies, etc., is to transport an external load from one location and deposit it at another.

ADDITIONAL MITIGATION - WITH PASSENGER

  • No additional mitigation is needed. 

SUMMATION

The External Load Working Group has worked diligently to flush out every concern associated with the carriage of external loads and passenger carrying for aircraft that do not have a TC/STC for this type of operation. It has been vigorous, almost fanatical, in debating the pros and cons, and in its examination of the risks and their mitigation. The WG recognizes that external load operations have been with us since the earliest days of Canadian aviation but were never addressed in regulations. Until the introduction of the Air Carrier Advisory Circular which provides the current exemption to allow external load and passengers, external loads have been a "do it but be quiet about it" type of operation.

There does not exist sufficient accident data to support statistical evidence that external load operations are a cause for accidents. The view of the Working Group is that leaving this issue in oblivion is, from a safety perspective, less effective than regulating it. This leads the WG to summarize that this activity, with adequate precautions to accommodate an acceptable level of safety, is desirable.

RECOMMENDATIONS

The following are the recommendations of the External Load Working Group.

  1. External load operations with/without passengers, private and commercial operations, for aeroplanes and helicopters class A loads, whose flight authority is not validated by a TC/STC, be permitted provided all the mitigation set out in this report is provided for in regulation, standards, advisory and training material.
  2. The Canadian Aviation Regulations be revised to accommodate Recommendation 1, as follows:
    1. create a Regulation in Subpart 602 to allow the carriage of external load with and without passengers, as per this report;
    2. create a section to 602 that will deem the flight authority to be valid when operating in accordance with 602, so as to satisfy the requirements of section 605.03;
    3. delete 703.25; and
    4. suggest to Technical Committee VII that 702.45 may be redundant following the introduction of the new 602 external load rules, and they may see it appropriate to delete it.
  3. Develop advisory material a per appendix "C" to supplement new external load regulations in 602.
  4. The maximum aircraft gross weight of the aircraft be reduced, in accordance with this report as follows.
    • With a successful climb performance check: 
      • no passengers - no weight penalty;
      • with passenger - 1 times the load weight.
    • Without a successful climb performance check:
      • no passengers - 2 times the load weight;
      • with passenger - 2 times the load weight.
    • And, in 'no passenger' external load operations, Transport Canada Civil Aviation be requested to evaluate the weight reduction of '2 times the weight', with a view to changing it to '1 times the weight' (see note 2).

CONCLUSION

It is the conclusion of the External Load WG that the external load issue is best addressed by taking the many years of Canadian Aviation external load experience, as reflected in the risk and mitigation portion of this report, and implementing the recommendations set out herein. This will help ensure that future external load operations receive the safety benefits derived from the Canadian aviation experience.

Appendix A - Proving Flight Requirements Aeroplanes
Appendix B - Proving Flight Requirements Helicopters
Appendix C - Advisory Material

Date modified:
2010-03-31