Powerplant Failure—Single-Engine Helicopter

Objective

The student will demonstrate ATP-level proficiency in recognizing and managing a powerplant failure in a single-engine helicopter by promptly entering autorotation, selecting an appropriate landing area, maintaining aircraft control within prescribed parameters, executing emergency procedures, and terminating the maneuver with a power recovery. Upon completion, the student will enter autorotation within one rotor revolution of simulated failure, maintain recommended autorotative airspeed ±5 knots, establish a proper approach pattern to a suitable landing area within the helicopter’s performance capability, complete appropriate emergency procedures, and execute a power recovery at a briefed altitude while maintaining positive aircraft control throughout. This lesson satisfies 14 CFR §61.159(b) ATP requirements and ACS task AT.V.C.

Content

Regulatory Framework

14 CFR §61.159(b) establishes ATP aeronautical experience requirements for helicopters, including cross-country, night, and instrument time. ATP candidates are expected to operate at the highest standard of airmanship, with emphasis on risk management and crew resource management principles applicable to single-pilot turbine operations.

14 CFR §91.3 grants the PIC final authority and responsibility for the operation. In an emergency such as powerplant failure, the PIC may deviate from regulations to the extent required to meet that emergency, but must submit a written report if requested by the FAA.

14 CFR §91.119 establishes minimum safe altitudes. During powerplant failure training, autorotations must be practiced in accordance with manufacturer limitations and at altitudes allowing safe power recovery without endangering persons or property on the surface.

Aerodynamic Principles of Autorotation

When the engine fails or is disconnected from the rotor system, the helicopter descends while air flows upward through the rotor system, providing energy to sustain rotor RPM. The rotor blade is divided into three regions:

Driven region (outboard): High rotational velocity causes the relative wind to strike from behind the blade’s rotational plane, creating drag that slows the rotor.

Driving region (center): The ascending airflow creates a forward relative wind component that strikes the blade from ahead of the rotational plane, producing a force with a forward component that accelerates the rotor.

Stall region (inboard): Low rotational velocity and high induced angles of attack can lead to blade stall, producing drag.

The driving region must produce sufficient energy to overcome drag from the driven and stall regions while maintaining rotor RPM within operational limits. The pilot controls this balance through collective pitch adjustments—lowering collective reduces blade angle of attack, moving the driving region outboard and increasing its efficiency.

Flight Characteristics During Autorotation

Rate of descent depends on rotor inertia, disc loading, density altitude, gross weight, and airspeed. Typical descent rates range from 1,500 to 2,500 FPM in turbine helicopters depending on configuration and weight.

Autorotative airspeed provides the minimum rate of descent and maximum glide distance. This speed varies by helicopter type and weight—Bell 206 approximately 60-70 KIAS, AS350 approximately 60 KIAS, Bell 407 approximately 70 KIAS. Maintaining this speed within ±5 knots is the ATP standard.

Rotor RPM management is critical. Too low: insufficient energy for flare and cushion. Too high: potential for blade stall during flare, overspeed limitations exceeded. The collective is the primary control—lower to increase RPM, raise to decrease RPM.

Glide ratio improves at best autorotative airspeed. Heavy helicopters and high density altitudes degrade glide performance. Wind affects ground track—headwinds reduce ground distance traveled, tailwinds extend it.

Entry Procedures

At the instant of powerplant failure (real or simulated), execute the following simultaneously and immediately:

1. Lower collective fully and smoothly to maintain rotor RPM within acceptable limits (typically green arc, manufacturer specified)
2. Apply right pedal to counteract reduction in engine torque and maintain trim
3. Establish slight aft cyclic to control airspeed decay and establish recommended autorotative airspeed
4. Maintain rotor RPM within limits through collective adjustments

Entry must occur within one rotor revolution of failure recognition. Delayed response results in rapid rotor RPM decay, potentially unrecoverable at low altitude. Think of rotor RPM as your energy bank account—the first deposit happens when you lower collective immediately.

Area and Landing Site Selection

Performance capability assessment: Consider helicopter gross weight, density altitude, wind conditions, obstacles, and approach path. A running landing may be required if conditions exceed hover capability. The selected area must be within glide range—use manufacturer performance charts and current conditions to determine glide ratio.

Suitable landing area criteria:

• Size adequate for helicopter dimensions plus safety margin (minimum 2x rotor diameter for confined areas)
• Surface suitable for landing—firm, level, free of obstacles, debris, and wires
• Approach and departure paths clear of obstacles
• Wind direction favorable (into wind preferred, crosswind within limits, downwind avoided)
• Emergency services accessible if actual emergency

Pattern establishment: Entry point, base leg, and final approach must account for altitude, wind drift, and energy management. High key and low key positions (borrowed from fixed-wing) provide checkpoints. Avoid undershooting (obstacle impact, insufficient energy) and overshooting (excessive energy state, long ground run or go-around requirement).

Terrain and obstacle considerations: Wires are the most insidious threat—difficult to see, often unmarked. Trees, buildings, towers, and uneven terrain affect approach angle and landing zone usability. Rotor clearance requires vigilance during all phases.

Failure Analysis and Restart Decision

Altitude permitting (typically above 1,000 AGL), assess the following:

Engine instruments: Check torque, N₁/N₂ (or manifold pressure and RPM), oil pressure, oil temperature, fuel flow, EGT/TGT. Look for indications of:

• Fuel starvation: low fuel flow, fuel pressure
• Compressor stall: rapid EGT rise, banging
• Mechanical failure: metal particles, oil pressure loss, abnormal vibration
• Governor failure: RPM fluctuations

Caution/warning lights: Master caution, engine fire, chip detector, hydraulics, fuel boost pump—each indicates different failure modes.

Restart viability: Consider altitude available (minimum 500 feet required for most restart attempts), cause of failure (mechanical failure = no restart, fuel selector position = restart likely), and risk vs. benefit. In training, evaluator will brief whether restart simulation is included.

Emergency checklist items: ATP candidates must demonstrate memory checklist completion appropriate to the aircraft type. Typical items include fuel boost pump on, check fuel quantity and selector, ignition check, starter engage (if parameters allow). The Pilot’s Operating Handbook (POH) or Rotorcraft Flight Manual (RFM) emergency section contains the definitive procedure.

Aircraft Control Throughout Maneuver

Positive control means maintaining desired flight path, attitude, and rotor RPM without abrupt inputs, over-controlling, or allowing parameters to exceed limits. ATP standards demand smooth, coordinated control inputs demonstrating professional competence.

Trim maintenance: Longitudinal trim keeps the fuselage level or slightly nose-down to prevent tail strike during flare and touchdown. Lateral trim prevents drift. Pedal trim maintains heading alignment with flight path.

Energy management: Altitude and rotor RPM are your only energy sources. Trade them wisely—use altitude to maintain RPM, use RPM to cushion landing. At low altitude, rotor RPM preservation is paramount. At higher altitude, establish best glide airspeed to maximize options.

Helicopter Configuration Devices

Landing gear (if retractable): Manufacturer procedures specify when to extend. Typically extended on downwind or base leg to ensure positive indication before landing. Extension increases drag—plan for steeper approach angle. FAA-approved procedures must be followed; some helicopters prohibit gear retraction below certain airspeeds or altitudes.

Hydraulics: Some helicopters allow hydraulics-off autorotations (Robinson R44, R66 simulate this). Control forces increase significantly. Others require hydraulics for controllability.

Governors and fuel control: Some turbine helicopters have manual fuel control modes used during practice autorotations to prevent engine spooling down. ATP candidates must understand the specific systems in the aircraft used.

Termination by Power Recovery

Briefed altitude: Evaluator will specify recovery altitude prior to flight (typically 50-100 feet AGL for experienced ATP candidates, higher for initial training). The recovery must be initiated at or above this altitude with sufficient energy to arrest descent and establish a climb or hover.

Power recovery procedure:

1. Flare at approximately 40-60 feet AGL (timing depends on airspeed and descent rate) by applying aft cyclic to reduce rate of descent and dissipate forward airspeed. Rotor RPM will increase during flare due to acceleration of blades.

2. Level the helicopter near briefed recovery altitude by reducing aft cyclic. Coordinate this with power application to avoid altitude loss.

3. Apply power smoothly by raising collective while monitoring rotor and engine RPM. Turbine engines require time to spool up—anticipate lag (2-3 seconds typical). Coordinate pedal input to maintain heading as torque increases.

4. Establish climb or hover: Adjust collective, cyclic, and pedals to achieve desired outcome. If performing running landing simulation, continue descent to simulate touchdown, then apply power to go around.

Common errors during power recovery: Late flare (insufficient energy dissipation, hard landing), excessive flare (tail strike, altitude gain followed by settling), abrupt collective application (rotor RPM droop, engine over-temp), inadequate pedal coordination (yaw excursion), delayed power application (altitude loss below briefed minimum).

Risk Management Emphasis

Pre-maneuver planning: Brief the maneuver thoroughly, including entry parameters, intended landing area, recovery altitude, and abort criteria. Ensure the practice area is suitable—adequate altitude, clear of congestion, identifiable forced landing areas.

Altitude awareness: Maintain continuous awareness of altitude above ground. Low-level autorotations are high-risk and not conducted during ATP training except in aircraft equipped with supplemental external visual systems (e.g., part 133 or 135 operators with specific OpSpecs). Standard training recoveries occur at safe altitudes.

Rotor RPM discipline: Operating outside the green arc jeopardizes safety. High rotor RPM during flare can lead to blade stall and mast bumping in teetering rotor systems. Low rotor RPM provides insufficient energy for landing flare.

Environmental considerations: Wind shear, turbulence, and downdrafts affect autorotative performance. High density altitude degrades performance significantly—descent rates increase, glide distance decreases.

Single-pilot resource management: In actual emergencies, manage workload by prioritizing fly the aircraft first, then troubleshooting, then communicating. Use all available resources—GPS for nearest airport, ELT preparation, passenger briefing if time permits.

Schedule

Equipment

Required References:

• FAA-S-ACS-ATP Helicopter Rating Airman Certification Standards (current edition)
• FAA-H-8083-21B Rotorcraft Flying Handbook
• Aircraft-specific Pilot’s Operating Handbook (POH) or Rotorcraft Flight Manual (RFM)
• 14 CFR Parts 61 and 91
• FAA-H-8083-9B Aviation Instructor’s Handbook (for CFI applicants)
• FAA-H-8083-2B Risk Management Handbook

Training Aircraft:

• Single-engine turbine helicopter (Bell 206, AS350, Bell 407, or similar) airworthy and equipped for autorotation training per manufacturer limitations
• Functional emergency checklist or POH readily accessible in cockpit

Visual Aids and Materials:

• Whiteboard or tablet for drawing rotor blade regions, force vectors, and approach patterns
• Model helicopter (if available) to demonstrate cyclic/collective/pedal coordination
• Sectional chart of practice area with suitable forced landing areas marked
• Aircraft performance charts for autorotative glide distance and descent rate

Personal Equipment:

• Aviation headset with intercom
• Fuel calculation tools (electronic or manual)
• Kneeboard with blank paper for student notes

Instructor Actions

1. Conduct ground instruction covering autorotation aerodynamics using the three blade regions model—explain how lowering collective moves the driving region outboard and increases net accelerating force, analogous to shifting a car into neutral going downhill to maintain engine RPM.

2. Demonstrate entry procedure on the ground using cockpit mockup or chair: simulate lowering collective, applying right pedal, and slight aft cyclic simultaneously—emphasize “one smooth motion, not three separate steps.”

3. Explain landing site selection criteria using sectional chart examples: identify suitable areas within glide range, discuss how to evaluate size, surface, obstacles, and wind during actual flight, and emphasize the decision must be made within first 5-10 seconds of failure recognition.

4. Teach failure analysis systematic flow: instruments from left to right, caution lights, sensory cues (sound, vibration, smell), then decide restart viability—remind students “fly the aircraft first, troubleshoot second, communicate third.”

5. Review emergency memory checklist items for the specific aircraft type: fuel boost pump, fuel selector, ignition, starter engagement parameters—have student verbalize the memory items without reference to demonstrate proficiency before flight.

6. Brief power recovery technique with emphasis on timing: flare initiation at 40-60 feet based on rate of descent, level at 100 feet (briefed altitude), smooth power application anticipating turbine spool-up lag, coordinated pedal to prevent yaw—use analogy of “catching the helicopter in a net” rather than slamming it.

7. Explain common errors and corrections before flight: delayed collective lowering (demonstrate rotor RPM decay rate on whiteboard), airspeed control issues (too fast increases descent rate, too slow risks settling), overshooting/undershooting (energy management), and abrupt power application (rotor droop).

8. Conduct pre-flight briefing in aircraft: point out visual references for altitude judgment, review go-around procedure if parameters are exceeded, establish abort criteria (rotor RPM outside limits, disorientation, traffic conflict), and confirm recovery altitude and communications plan.

9. Demonstrate first autorotation from cruise flight at 2,500 AGL: announce “simulated engine failure,” smoothly lower collective while narrating “collective down, right pedal, airspeed 65 knots, rotor RPM in the green,” select landing area ahead and announce choice, establish approach pattern, perform clearing turn while maintaining parameters, initiate flare at 60 feet, level at 100 feet, smoothly apply power while stating “power recovering, check rotor RPM, adjust collective, add left pedal for torque.”

10. Observe student’s first attempt providing minimal intervention: allow student to make entry (monitor rotor RPM closely, be ready to assist), call out altitude and airspeed deviations (“altitude 2,000, airspeed 70, need to lower nose slightly”), prompt for landing area selection (“where are you going to land?”), monitor approach management, call altitudes during recovery phase (“100 feet, initiate recovery now”).

11. Provide progressive coaching on subsequent repetitions: reduce callouts as student improves, focus on one or two refinements per iteration (“this time focus on getting collective down within half a second,” or “work on maintaining 65 knots exactly during descent”), and use positive reinforcement when standards are met (“excellent entry, rotor RPM stayed in the green throughout”).

12. Demonstrate variations if student achieves basic proficiency: autorotation with turn to landing area, increased descent rate by slowing below best glide speed, effect of collective adjustments on rotor RPM, and simulated governor-off autorotation per POH procedures.

13. Conduct in-flight debrief while returning to airport: ask student to self-assess performance (“which entry felt most controlled?” “what parameter gave you the most trouble?”), confirm understanding of standards, and emphasize integration of this maneuver into overall emergency management mindset.

14. Lead post-flight discussion covering trend analysis: show student gradual improvement in entry timing, airspeed control consistency, and recovery smoothness using notes from flight; address persistent errors with corrective strategies; assign mental practice exercise of visualizing perfect autorotation sequence.

15. Document lesson in student’s training record: note number of autorotations completed, specific parameters achieved or missed, areas requiring additional practice, and readiness for checkride evaluation of this task.

Student Actions

1. Actively participate in ground instruction by asking clarifying questions about blade regions, force vectors, and energy management concepts—demonstrate understanding by explaining back to instructor how lowering collective affects rotor RPM.

2. Practice emergency memory checklist items verbally until able to recite all items in correct sequence without reference to POH or checklist—critical for ATP-level performance expectation.

3. Study aircraft-specific autorotation procedures in POH/RFM prior to lesson, noting recommended entry airspeed, rotor RPM limits, descent rate expectations, and any unique configuration requirements.

4. Perform pre-flight inspection with particular attention to rotor system integrity, engine controls freedom of movement, and fuel system security—since powerplant failure training stresses systems differently than normal operations.

5. Verbalize pre-maneuver clearing procedures aloud: “clearing left, clearing right, clearing above, clearing below, area is clear”—establish this habit before each practice autorotation.

6. Execute first autorotation entry when instructor simulates failure by announcing “engine failure”: immediately lower collective smoothly to full down position, apply right pedal to maintain trim, apply slight aft cyclic to establish 65 knots (or POH-recommended airspeed), scan rotor RPM and confirm in green arc.

7. Announce landing area selection within 5 seconds of entry: point and state “landing in that field at 10 o’clock, 1 mile”—demonstrate decision-making process aloud so instructor can evaluate judgment.

8. Maintain autorotative airspeed within ±5 knots using cyclic adjustments: cross-check airspeed indicator frequently, make small pitch corrections to hold target speed, resist temptation to climb or dive excessively.

9. Manage rotor RPM using collective adjustments: if RPM increases above green arc, raise collective slightly; if RPM decreases toward yellow arc, lower collective slightly—develop fine motor control and immediate response to tachometer indications.

10. Establish approach pattern to selected landing area: fly downwind if altitude permits, turn base leg accounting for wind drift, roll out on final aligned with wind direction and landing area centerline, adjust aim point to avoid undershooting or overshooting.

11. Complete emergency checklist items (simulated or actual per briefing): state each item aloud “fuel boost pump—on, fuel selector—checked, ignition—checked”—demonstrate systematic flow even under stress of managing descent.

12. Initiate flare at approximately 40-60 feet AGL by applying aft cyclic smoothly: feel rotor RPM increase as blades accelerate, monitor altitude loss rate decreasing, dissipate forward airspeed, prepare for power application.

13. Execute power recovery at briefed altitude (100 feet AGL): level helicopter by reducing aft cyclic, smoothly raise collective while monitoring rotor and engine RPM, add left pedal progressively as torque increases, adjust cyclic to maintain position over ground reference.

14. Establish climb after power recovery: verify positive rate of climb on VSI and altimeter, trim helicopter for normal climb attitude, confirm all engine parameters normal, perform clearing turn to check for traffic.

15. Conduct self-assessment after each repetition: mentally review entry timing, airspeed control, site selection quality, approach management, and recovery smoothness—identify one specific item to improve on next attempt and communicate this to instructor.

16. Respond to instructor feedback by implementing suggested corrections immediately on next autorotation: if instructor notes late collective lowering, focus mental attention on speed of initial response; if airspeed control was inconsistent, dedicate more scan time to ASI.

17. Demonstrate improvement over successive repetitions: show consistent entry within one rotor revolution, maintain airspeed within ±3 knots (tighter than ATP minimum standard), select landing areas with better judgment of suitability, execute smoother power recoveries with minimal altitude deviation.

18. Ask specific questions about observed results: “I felt the helicopter start to yaw right during power application—is that normal or did I add pedal too slowly?” or “The flare seemed late on that one—should I have started at 70 feet instead of 50?”

19. Practice verbalization technique during one autorotation by narrating all actions aloud: “collective down, right pedal, airspeed 65, rotor RPM green, selecting field ahead, turning base, checking altitude 500 feet, turning final, 200 feet, flare initiate, level, power applying, climb established”—this demonstrates systematic thinking and helps encode correct sequence.

20. Complete post-flight review by documenting lesson experience in personal logbook with specific notes: entry timing improvements, consistent parameters achieved, areas still needing refinement, questions to research before next lesson.

Completion Standards

The lesson is complete when the student demonstrates ATP-level proficiency in powerplant failure management consistent with FAA-S-ACS-ATP Task AT.V.C by meeting all of the following standards:

1. Exhibits adequate knowledge of autorotation aerodynamics by correctly explaining the three blade regions (driven, driving, stall), the effect of collective position on rotor RPM, factors affecting rate of descent and glide distance, and aircraft-specific emergency procedures during the ground instruction debrief.

2. Enters autorotation promptly within one rotor revolution of simulated powerplant failure by lowering collective smoothly and completely to maintain rotor RPM within manufacturer-specified green arc limits throughout the maneuver (typically 90-107% Nr depending on helicopter type).

3. Establishes and maintains recommended autorotative airspeed within ±5 knots of POH/RFM specified best glide speed for the helicopter’s weight and configuration, making smooth cyclic adjustments to correct deviations without exceeding tolerance.

4. Maintains proper longitudinal trim throughout the descent by keeping the fuselage level or slightly nose-down attitude, preventing tail-low attitude that could result in tail strike during landing flare.

5. Selects a suitable landing area within the performance capability of the helicopter by identifying an area that is:

   • Within autorotative glide range based on current altitude and wind conditions
   • Adequate size for safe landing (minimum 2x rotor diameter for confined areas)
   • Free of obstacles, wires, and hazardous terrain
   • Accessible considering approach and departure paths
   • Oriented to land into the wind or within crosswind limitations

6. Establishes proper flight pattern to the selected landing area by planning and flying a pattern that:

   • Accounts for altitude energy management (high key/low key positions as appropriate)
   • Compensates for wind drift to maintain ground track alignment
   • Provides obstacle clearance on all legs
   • Positions the helicopter for final approach aligned with wind direction
   • Avoids undershooting (insufficient energy state, obstacle hazard) or overshooting (excessive energy, go-around requirement)

7. Determines cause of simulated failure when altitude permits (above 1,000 feet AGL) by systematically checking engine instruments (torque, N₁/N₂, oil pressure/temperature, fuel flow, EGT/TGT), caution/warning lights, fuel system status, and other indications, then making a reasoned assessment of restart viability.

8. Performs emergency memory checklist items appropriate to the specific helicopter type without reference to written checklist, in the correct sequence, and at the appropriate time during the descent—demonstrating ATP-level systems knowledge and emergency procedure proficiency.

9. Maintains positive helicopter control throughout the entire maneuver by:

   • Coordinating all flight control inputs smoothly
   • Preventing uncommanded yaw, roll, or pitch excursions
   • Maintaining rotor RPM within green arc continuously
   • Keeping the helicopter within ±10° of desired heading during descent
   • Demonstrating professional control touch without over-controlling

10. Uses helicopter configuration devices per manufacturer recommendations and FAA-approved procedures by extending landing gear (if retractable) at the appropriate point in the pattern, verifying positive extension indication, and accounting for increased drag in approach planning.

11. Terminates autorotation with power recovery at the altitude briefed by the evaluator (typically 50-100 feet AGL) or higher by:

    • Initiating flare at appropriate altitude (40-60 feet) to reduce rate of descent
    • Leveling the helicopter at or above briefed recovery altitude
    • Smoothly applying power by raising collective while monitoring rotor and engine RPM
    • Coordinating left pedal application to counteract increasing torque and maintain heading ±10°
    • Establishing a positive rate of climb or stabilized hover
    • Completing recovery without descending below briefed minimum altitude
    • Preventing rotor RPM droop during power application (maintaining above 90% Nr minimum)

12. Demonstrates risk management by verbalizing situational awareness of altitude above terrain, proximity to suitable landing areas, wind conditions affecting glide performance, potential obstacles in the approach path, and personal proficiency limitations—showing ATP-level aeronautical decision-making throughout the maneuver.

The student must meet all completion standards on at least two consecutive autorotations with minimal instructor coaching to demonstrate consistency and proficiency at ATP standards required for ACS task AT.V.C. Any exceedance of rotor RPM limitations, descent below briefed recovery altitude, or loss of positive aircraft control constitutes unsatisfactory performance requiring additional training.