Appendix F to Part 91—Helicopter Flight Recorder Specifications
Installed system 1 minimum accuracy (to recovered data)
Sampling interval (per second)
Resolution 3 read out
1 When data sources are aircraft instruments (except altimeters) of acceptable quality to fly the aircraft the recording system excluding these sensors (but including all other characteristics of the recording system) shall contribute no more than half of the values in this column.
2 Per cent of full range.
3 This column applies to aircraft manufactured after October 11, 1991.
4 For all aircraft manufactured on or after April 6, 2012, the sampling interval per second is 4.
Relative Time (From Recorded on Prior to Takeoff)
4 hr minimum
±0.125% per hour
VM in to VD (KIAS) (minimum airspeed signal attainable with installed pilot-static system)
±5% or ±10 kts., whichever is greater
−1,000 ft. to 20,000 ft. pressure altitude
±100 to ±700 ft. (see Table 1, TSO C51-a)
25 to 150 ft.
−3g to 6g
±0.2g in addition to ±0.3g maximum datum
4 (or 1 per second where peaks, ref. to 1g are recorded)
±1.5% max. range excluding datum error of ±5%
100% of usable range
±60 or 100% of usable range, whichever is greater
±10% Resolution 250 fpm below 12,000 ft. indicated