RHL - Repetitive Heavy Lift
REL - Repetitive External Lift
Sikorsky and GE use RHL and REL cycles in a similar manner as Bell utilises the RIN cycle count. Essentially a means of counting load cycles, to allow for a variable in the flight hour/lift cycle equation formulated on Ground-Air-Ground (GAG) cycles. As most ultimate lives are calculated using straight certification conversions between cycles and flight hours, this essentially takes the calculation in the opposite direction, to ensure the integrity of the component is not compromised.
Typically in RHL/REL operations there is a criteria based upon lifts per hour (or a straight lift cycle count), which is applied to adjust for component ultimate life in order to compensate for high cycle fatigue. In other products utilised in these applications, this has been accomplished and the mandated life limits adjusted accordingly.
I believe the CT7/T-700 was determined to adequately meet the requirements for RHL operation without any life-limit adjustment.
Note 13 of the TCDS refers to life limits, but I don't know the content of that section. With the 214ST now in the firefighting arena, there are two variants of this engine operating in this environment, so maybe this will be reviewed?
Anyone know anything more about this incident? This series engine always seemed to be very good, is anyone aware of any other problems of this nature?
The
S-70A is certified under 21.25(a)(2), as a Restricted Category aircraft. Non Army modifications must comply with Part 29. As a Public Use operator, LA County is free to operate this aircraft in any application they desire.
Sec. 21.25
Issue of type certificate: restricted category aircraft.
[(a) An applicant is entitled to a type certificate for an aircraft in the restricted category for special purpose operations if he shows compliance with the applicable noise requirements of Part 36 of this chapter, and if he shows that no feature or characteristic of the aircraft makes it unsafe when it is operated under the limitations prescribed for its intended use, and that the aircraft--]
(1) Meets the airworthiness requirements of an aircraft category except those requirements that the Administrator finds inappropriate for the special purpose for which the aircraft is to be used; or
(2) Is of a type that has been manufactured in accordance with the requirements of and accepted for use by, an Armed Force of the United States and has been later modified for a special purpose.
(b) For the purposes of this section, "special purpose operations" includes--
(1) Agricultural (spraying, dusting, and seeding, and livestock and predatory animal control);
(2) Forest and wildlife conservation;
(3) Aerial surveying (photography, mapping, and oil and mineral exploration);
(4) Patrolling (pipelines, power lines, and canals);
(5) Weather control (cloud seeding);
(6) Aerial advertising (skywriting, banner towing, airborne signs and public address systems); and
(7) Any other operation specified by the Administrator.