The R22 Maintenance Manual - Section 3 - paragraph 3.002 states:
It is the operator’s responsibility to maintain accurate time-in-service records of the airframe and life-limited components. An hourmeter activated by engine oil pressure is standard equipment in the R22 helicopter and is an acceptable means of recording time-in-service.
later in the same section it states:
The approved overhaul intervals and the fatigue service lives listed in the Airworthiness Limitations Section are based on FAA Advisory Circular 20-95 which assume that 10.5% of the operating time will be in autorotation, runup, or shutdown. Therefore, if an hourmeter activated by the collective control is used to record the time-in-service, the values recorded must be multiplied by 1.12 when determining replacement times for life-limited components, engine and airframe overhaul periods, and other periodic inspection requirements.
The R44 Maintenance Manual - Section 3 - paragraph 3.002 states:
It is the operator’s responsibility to maintain accurate time-in-service records for the airframe, engine, and life-limited components. An hourmeter activated by engine oil pressure is standard equipment on earlier R44 helicopters and is an acceptable means of recording time in service. Later helicopters are equipped with an hourmeter activated by a combination of oil pressure and up collective; the hourmeter will record time only when engine oil pressure exists and the collective is raised.
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