Federal regulations · Through 2026-08-25 · Newer source version available

14 CFR Appendix E to Part 135: Appendix E to Part 135—Helicopter Flight Recorder Specifications

Parameters Range Accuracy sensor input to DFDR readout Sampling interval (per second) Resolution 2 read out
Time (GMT) 24 Hrs ±0.125% Per Hour 0.25 (1 per 4 seconds) 1 sec
Altitude −1,000 ft to max certificated altitude of aircraft ±100 to ±700 ft (See Table 1, TSO-C51a) 1 5′ to 30′.
Airspeed As the installed measuring system ±3% 1 1 kt
Heading 360° ±2° 1 0.5°.
Normal Acceleration (Vertical) −3g to + 6g ±1% of max range excluding datum error of ±5% 8 0.01g
Pitch Attitude ±75° ±2° 2 0.5°
Roll Attitude ±180° ±2° 2 0.5°.
Radio Transmitter Keying On-Off (Discrete) 1 0.25 sec
Power in Each Engine: Free Power Turbine Speed and Engine Torque 0-130% (power Turbine Speed) Full range (Torque) ±2% 1 speed 1 torque (per engine) 0.2% 1 to 0.4% 1
Main Rotor Speed 0-130% ±2% 2 0.3% 1
Altitude Rate ±6,000 ft/min As installed 2 0.2% 1
Pilot Input—Primary Controls (Collective, Longitudinal Cyclic, Lateral Cyclic, Pedal) 3 Full range ±3% 2 0.5% 1
Flight Control Hydraulic Pressure Low Discrete, each circuit 1
Flight Control Hydraulic Pressure Selector Switch Position, 1st and 2nd stage Discrete 1
AFCS Mode and Engagement Status Discrete (5 bits necessary) 1
Stability Augmentation System Engage Discrete 1
SAS Fault Status Discrete 0.25
Main Gearbox Temperature Low As installed As installed 0.25 0.5% 1
Main Gearbox Temperature High As installed As installed 0.5 0.5% 1
Controllable Stabilator Position Full Range ±3% 2 0.4% 1.
Longitudinal Acceleration ±1g ±1.5% max range excluding datum error of ±5% 4 0.01g.
Lateral Acceleration ±1g ±1.5% max range excluding datum of ±5% 4 0.01g.
Master Warning Discrete 1
Nav 1 and 2 Frequency Selection Full range As installed 0.25
Outside Air Temperature −50 °C to + 90 °C ±2° c 0.5 0.3° c
1 Per cent of full range.
2 This column applies to aircraft manufactured after October 11, 1991.
3 For all aircraft manufactured on or after December 6, 2010, the sampling interval per second is 4.

Where this section sits in the code

Title 14—Aeronautics and Space
CHAPTER I—FEDERAL AVIATION ADMINISTRATION, DEPARTMENT OF TRANSPORTATION
SUBCHAPTER G—AIR CARRIERS AND OPERATORS FOR COMPENSATION OR HIRE: CERTIFICATION AND OPERATIONS
PART 135—OPERATING REQUIREMENTS: COMMUTER AND ON DEMAND OPERATIONS AND RULES GOVERNING PERSONS ON BOARD SUCH AIRCRAFT

Parameters Range Accuracy sensor input to DFDR readout Sampling interval (per second) Resolution 2 read out

Time (GMT) 24 Hrs ±0.125% Per Hour 0.25 (1 per 4 seconds) 1 sec

Altitude −1,000 ft to max certificated altitude of aircraft ±100 to ±700 ft (See Table 1, TSO-C51a) 1 5′ to 30′.

Airspeed As the installed measuring system ±3% 1 1 kt

Heading 360° ±2° 1 0.5°.

Normal Acceleration (Vertical) −3g to + 6g ±1% of max range excluding datum error of ±5% 8 0.01g

Pitch Attitude ±75° ±2° 2 0.5°

Roll Attitude ±180° ±2° 2 0.5°.

Radio Transmitter Keying On-Off (Discrete) 1 0.25 sec

Power in Each Engine: Free Power Turbine Speed and Engine Torque 0-130% (power Turbine Speed) Full range (Torque) ±2% 1 speed 1 torque (per engine) 0.2% 1 to 0.4% 1

Main Rotor Speed 0-130% ±2% 2 0.3% 1

Altitude Rate ±6,000 ft/min As installed 2 0.2% 1

Pilot Input—Primary Controls (Collective, Longitudinal Cyclic, Lateral Cyclic, Pedal) 3 Full range ±3% 2 0.5% 1

Flight Control Hydraulic Pressure Low Discrete, each circuit 1

Flight Control Hydraulic Pressure Selector Switch Position, 1st and 2nd stage Discrete 1

AFCS Mode and Engagement Status Discrete (5 bits necessary) 1

Stability Augmentation System Engage Discrete 1

SAS Fault Status Discrete 0.25

Main Gearbox Temperature Low As installed As installed 0.25 0.5% 1

Main Gearbox Temperature High As installed As installed 0.5 0.5% 1

Controllable Stabilator Position Full Range ±3% 2 0.4% 1.

Longitudinal Acceleration ±1g ±1.5% max range excluding datum error of ±5% 4 0.01g.

Lateral Acceleration ±1g ±1.5% max range excluding datum of ±5% 4 0.01g.

Master Warning Discrete 1

Nav 1 and 2 Frequency Selection Full range As installed 0.25

Outside Air Temperature −50 °C to + 90 °C ±2° c 0.5 0.3° c

1 Per cent of full range.

2 This column applies to aircraft manufactured after October 11, 1991.

3 For all aircraft manufactured on or after December 6, 2010, the sampling interval per second is 4.

Collected 2026-08-27T02:24:20Z. Source file · JSON

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