§ 27.865 External loads. ( a ) It must be shown by analysis, test, or both, that the rotorcraft external load attaching means for rotorcraft-load combinations to be used for nonhuman external cargo applications can withstand a limit static load equal to 2.5, or some lower load factor approved under §§ 27.337 through 27.341, multiplied by the maximum external load for which authorization is requested. It must be shown by analysis, test, or both that the rotorcraft external load attaching means and corresponding personnel carrying device system for rotorcraft-load combinations to be used for human external cargo applications can withstand a limit static load equal to 3.5 or some lower load factor, not less than 2.5, approved under §§ 27.337 through 27.341, multiplied by the maximum external load for which authorization is requested. The load for any rotorcraft-load combination class, for any external cargo type, must be applied in the vertical direction. For jettisonable external loads of any applicable external cargo type, the load must also be applied in any direction making the maximum angle with the vertical that can be achieved in service but not less than 30°. However, the 30° angle may be reduced to a lesser angle if— ( 1 ) An operating limitation is established limiting external load operations to such angles for which compliance with this paragraph has been shown; or
( 2 ) It is shown that the lesser angle can not be exceeded in service.
( b ) The external load attaching means, for jettisonable rotorcraft-load combinations, must include a quick-release system to enable the pilot to release the external load quickly during flight. The quick-release system must consist of a primary quick release subsystem and a backup quick release subsystem that are isolated from one another. The quick-release system, and the means by which it is controlled, must comply with the following: ( 1 ) A control for the primary quick release subsystem must be installed either on one of the pilot's primary controls or in an equivalently accessible location and must be designed and located so that it may be operated by either the pilot or a crewmember without hazardously limiting the ability to control the rotorcraft during an emergency situation.
( 2 ) A control for the backup quick release subsystem, readily accessible to either the pilot or another crewmember, must be provided.
( 3 ) Both the primary and backup quick release subsystems must— ( i ) Be reliable, durable, and function properly with all external loads up to and including the maximum external limit load for which authorization is requested.
( ii ) Be protected against electromagnetic interference (EMI) from external and internal sources and against lightning to prevent inadvertent load release. ( A ) The minimum level of protection required for jettisonable rotorcraft-load combinations used for nonhuman external cargo is a radio frequency field strength of 20 volts per meter.
( B ) The minimum level of protection required for jettisonable rotorcraft-load combinations used for human external cargo is a radio frequency field strength of 200 volts per meter.
( iii ) Be protected against any failure that could be induced by a failure mode of any other electrical or mechanical rotorcraft system.
( c ) For rotorcraft-load combinations to be used for human external cargo applications, the rotorcraft must— ( 1 ) For jettisonable external loads, have a quick-release system that meets the requirements of paragraph (b) of this section and that— ( i ) Provides a dual actuation device for the primary quick release subsystem, and
( ii ) Provides a separate dual actuation device for the backup quick release subsystem;
( 2 ) Have a reliable, approved personnel carrying device system that has the structural capability and personnel safety features essential for external occupant safety;
( 3 ) Have placards and markings at all appropriate locations that clearly state the essential system operating instructions and, for the personnel carrying device system, the ingress and egress instructions;
( 4 ) Have equipment to allow direct intercommunication among required crewmembers and external occupants; and
( 5 ) Have the appropriate limitations and procedures incorporated in the flight manual for conducting human external cargo operations.
( d ) The critically configured jettisonable external loads must be shown by a combination of analysis, ground tests, and flight tests to be both transportable and releasable throughout the approved operational envelope without hazard to the rotorcraft during normal flight conditions. In addition, these external loads must be shown to be releasable without hazard to the rotorcraft during emergency flight conditions.
( e ) A placard or marking must be installed next to the external-load attaching means clearly stating any operational limitations and the maximum authorized external load as demonstrated under § 27.25 and this section.
( f ) The fatigue evaluation of § 27.571 of this part does not apply to rotorcraft-load combinations to be used for nonhuman external cargo except for the failure of critical structural elements that would result in a hazard to the rotorcraft. For rotorcraft-load combinations to be used for human external cargo, the fatigue evaluation of § 27.571 of this part applies to the entire quick release and personnel carrying device structural systems and their attachments.
[Amdt. 27-11, 41 FR 55469, Dec. 20, 1976, as amended by Amdt. 27-26, 55 FR 8001, Mar. 6, 1990; Amdt. 27-36, 64 FR 43019, Aug. 6, 1999]