14 CFR Appendix F to Part 91, Helicopter Flight Recorder Specifications

Appendix F to Part 91 - Helicopter Flight Recorder Specifications
Parameters Range Installed system 1 minimum accuracy (to recovered data) Sampling interval (per second) Resolution 3 read out
Relative Time (From Recorded on Prior to Takeoff) 4 hr minimum ±0.125% per hour 1 1 sec.
Indicated Airspeed VM in to VD (KIAS) (minimum airspeed signal attainable with installed pilot-static system) ±5% or ±10 kts., whichever is greater 1 1 kt.
Altitude −1,000 ft. to 20,000 ft. pressure altitude ±100 to ±700 ft. (see Table 1, TSO C51-a) 1 25 to 150 ft.
Magnetic Heading 360° ±5° 1
Vertical Acceleration −3g to 6g ±0.2g in addition to ±0.3g maximum datum 4 (or 1 per second where peaks, ref. to 1g are recorded) 0.05g.
Longitudinal Acceleration ±1.0g ±1.5% max. range excluding datum error of ±5% 2 0.03g.
Pitch Attitude 100% of usable range ±2° 1 0.8°
Roll Attitude ±60 or 100% of usable range, whichever is greater ±2° 1 0.8°
Altitude Rate ±8,000 fpm ±10% Resolution 250 fpm below 12,000 ft. indicated 1 250 fpm below 12,000.
Engine Power, Each Engine
Main Rotor Speed Maximum Range ±5% 1 1%2.
Free or Power Turbine Maximum Range ±5% 1 1%2.
Engine Torque Maximum Range ±5% 1 1%2.
Flight Control Hydraulic Pressure
Primary (Discrete) High/Low 1
Secondary - if applicable (Discrete) High/Low 1
Radio Transmitter Keying (Discrete) On/Off 1
Autopilot Engaged (Discrete) Engaged or Disengaged 1
SAS Status-Engaged (Discrete) Engaged or Disengaged 1
SAS Fault Status (Discrete) Fault/OK 1
Flight Controls
Collective 4 Full range ±3% 2 1%2.
Pedal Position 4 Full range ±3% 2 1%2.
Lat. Cyclic 4 Full range ±3% 2 1%2.
Long. Cyclic 4 Full range ±3% 2 1%2.
Controllable Stabilator Position 4 Full range ±3% 2 1%2.

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.

[Doc. No. 18334, 54 FR 34328, Aug. 18, 1989; 54 FR 41211, Oct. 5, 1989; 54 FR 53036, Dec. 26, 1989; Amdt. 91-300, 73 FR 12565, Mar. 7, 2008; 73 FR 15280, Mar. 21, 2008; Amdt. 91-313, 75 FR 17046, Apr. 5, 2010]

This is a list of United States Code sections, Statutes at Large, Public Laws, and Presidential Documents, which provide rulemaking authority for this CFR Part.

This list is taken from the Parallel Table of Authorities and Rules provided by GPO [Government Printing Office].

It is not guaranteed to be accurate or up-to-date, though we do refresh the database weekly. More limitations on accuracy are described at the GPO site.


United States Code
U.S. Code: Title 49 - TRANSPORTATION

§ 106 - Federal Aviation Administration

§ 1155 - Aviation penalties

§ 40103 - Sovereignty and use of airspace

§ 40113 - Administrative

§ 40120 - Relationship to other laws

§ 44101 - Operation of aircraft

§ 44111 - Modifications in registration and recordation system for aircraft not providing air transportation

§ 44701 - General requirements

§ 44704 - Type certificates, production certificates, airworthiness certificates,,11 So in original. and design and production organization certificates

§ 44709 - Amendments, modifications, suspensions, and revocations of certificates

§ 44711 - Prohibitions and exemption

§ 44712 - Emergency locator transmitters

§ 44715 - Controlling aircraft noise and sonic boom

§ 44716 - Collision avoidance systems

§ 44717 - Aging aircraft

§ 44722 - Aircraft operations in winter conditions

§ 46306 - Registration violations involving aircraft not providing air transportation

§ 46315 - Lighting violations involving transporting controlled substances by aircraft not providing air transportation

§ 46316 - General criminal penalty when specific penalty not provided

§ 46504 - Interference with flight crew members and attendants

§ 46506 - Application of certain criminal laws to acts on aircraft

§ 46507 - False information and threats

§ 47122 - Administrative

§ 47508 - Noise standards for air carriers and foreign air carriers providing foreign air transportation

§ 47528 - Prohibition on operating certain aircraft not complying with stage 3 noise levels

§ 47529 - Nonaddition rule

§ 47530 - Nonapplication of sections 47528(a)–(d) and 47529 to aircraft outside the 48 contiguous States

§ 47531 - Penalties

§ 47534 - Prohibition on operating certain aircraft weighing 75,000 pounds or less not complying with stage 3 noise levels

Statutes at Large