Robinson Safety Notices

Robinson Safety Notices

SN-1 - Inadvertent Actuation of Mixture Control in Flight

Always reach around the left side of the cyclic when actuating trim. Use the mixture control guard.

SN-9 - Many Accidents Involve Dynamic Rollover

To avoid dynamic rollover:

• Only practice hover autorotations into less than 10 knots of wind.
• Avoid obstacles on the ground.
• Use a two-step liftoff.
• Hover at least five feet above ground when practicing sideward or rearward flight.

To correct, quickly apply down collective.

SN-10 - Fatal Accidents Caused by Low RPM Rotor Stall

The conditioned reflex to low rotor RPM must be to simultaneously add throttle and lower collective. In forward flight, apply aft cyclic.

SN-11 - Low-G Pushovers - Extremely Dangerous

Never perform a low-G pushover.

To prevent mast bumping in a low-G situation, apply an immediate gentle aft cycle before correcting right roll.

SN-13 - Do Not Attach Items to the Skids

Do not attempt to carry any external load or object attached to the landing gear.

SN-15 - Fuel Exhaustion Can Be Fatal

To avoid fuel exhaustion:

• Never rely solely on the fuel gage or low fuel warning light.
• Check fuel level in the tanks visually.
• Drain fuel to check for water contamination during preflight.
• Continually check fuel levels in flight.
• Always land to refuel before the main tank fuel gage reads less than 1/4 full.

SN-16 - Power Lines Are Deadly

• Fly directly over towers when crossing power lines.
• Maintain at least 500 feet AGL when possible.

SN-17 - Never Exit Helicopter With Engine Running

• Never exit helicopter with engine running.
• Hold controls when boarding passengers.
• Never land in tall dry grass.

SN-18 - Loss of Visibility Can Be Fatal

• Take corrective action before visibility is lost.
• Use good judgement and land in bad weather.

SN-19 - Flying Low Over Water is Very Hazardous

Flying over water can interfere with normal depth perception. Maintain 500 feet AGL whenever possible and avoid maneuvers below 200 feet AGL.

SN-20 - Beware of Demonstration or Initial Training Flights

Instructors should be prepared for when the student makes sudden incorrect control movements.

SN-22 - Vortex Ring State Catches Many Pilots by Surprise

To avoid vortex ring state, reduce rate of descent before reducing airspeed. A good rule to follow is never allow your airspeed to be less than 30 knots until your rate-of-descent is less than 300 feet per minute.

There are two techniques to recover from vortex ring state:

• Reduce collective to reduce downwash, then forward cyclic to fly forward out of the downwash. This can result in significant altitude loss, which may not be acceptable on an approach.
• Lateral cyclic to fly sideways out of the downwash, assisted by tail rotor thrust. This is known as the Vuichard recovery.

SN-23 - Walking Into Tail Rotor Can Be Fatal

• Passengers must be instructed to maintain eye contact when approaching the helicopter.
• Always turn on strobe when rotors are turning.
• Be careful of unseen people approaching from the rear.

SN-24 - Low RPM Rotor Stall Can Be Fatal

Rotor stall accidents most often occur close to the ground, but a rotor stall above 40 or 50 feet AGL is most likely to be fatal.

When the rotor stalls, the retreating blade stalls first, resulting in “rotor blow-back”, then the upward flow of air from under the tail causes a dive.

SN-25 - Carburetor Ice

Carburetor ice can occur at OATs as high as 30°C.

Even in dry air, local conditions such as a nearby body of water can be conducive to carburetor ice.

When in doubt, assume conditions are conducive to carburetor ice and apply carb heat as required.

Use full carb heat during run-up to preheat the induction system.

Full carb heat requires approximately 1.5” Hg. The engine can produce full power at lower altitudes with full heat, but at high altitudes, avoid using more heat than required to avoid reaching full throttle at less than maximum power.

SN-26 - Night Flight Plus Bad Weather Can Be Deadly

There are many hazards related to night flight. Never fly at night unless you have clear weather with unlimited or very high ceilings and plenty of celestial or ground lights for reference.

SN-27 - Surprise Throttle Chops Can Be Deadly

Instructors should announce “power failure” before smoothly rolling off the throttle and keeping the right leg muscles tight in case the student presses the wrong pedal.

Simulated engine failures should be performed within glide distance of a safe touchdown area.

SN-28 - Listen For Impending Bearing Failure

An impending ball bearing failure is usually preceded by a noticeable increase in noise, typically several hours before the bearing completely fails.

During startup, uncover one ear and listen to the sound of the drive system. Upon hearing an unusual noise, immediately ground the aircraft and have bearings inspected.

Do not rely on telatemps to indicate bearing failure, as they may only black out once the bearing starts to disintegrate.

If the clutch light flickers or stays on for more than 10 seconds, pull the clutch circuit breaker and reduce power. Make a precautionary landing to inspect drive system and be prepared to enter autorotation.

SN-29 - Airplane Pilots High Risk When Flying Helicopters

Airplane pilots must be carefully trained to never abruptly push the cyclic forward.

SN-30 - Loose Objects Can Be Fatal

Loose objects flying out of the cabin and striking the tail rotor can cause failure of the tail rotor blade, resulting in a fatal accident.

• Ensure fuel caps and door hinge pins are secure.
• Stow or secure all loose objects in the cabin.
• Firmly latch all doors.
• Never fly with a left door removed.

SN-31 - Governor Can Mask Carb Ice

Apply carb heat as required to keep CAT out of yellow arc.

Apply full carb heat when manifold pressure is below 18 inches.

Carb heat assist will reduce carb heat when you lift off to a hover and may require readjustment in flight.

SN-32 - High Winds or Turbulence

Pilots should avoid flight in high winds or turbulence due to increased risk of mast bumping.

• Reduce airspeed to 60-70 knots in turbulence.
• Rest forearm on leg or apply a small amount of cyclic friction to minimum unintentional inputs.
• Do not overcontrol
• Avoid flying on the downwind side of obstacles where turbulence will likely be most severe.

SN-33 - Drive Belt Slack

Check drive belt slack during preflight to avoid belts jumping out of sheave grooves during engine start. The belt should deflect approximately 1.5” when pressed on just above the fan scroll.

After engine start, engage clutch and verify rotor turns within 5 seconds. If rotor does not turn within 5 seconds, shut down and have actuator adjusted.

SN-34 - Photo Flights - Very High Risk

Aerial survey and photo flights should only be conducted by well trained, experience pilots who:

• Have at least 500 hours PIC in helicopters and over 100 hours in the model flown.
• Have extensive training in both low RPM and settling-with-power recovery techniques.
• Are willing to say no to the observer or photographer.

SN-35 - Flying Near Broadcast Towers

High power radio broadcast towers (typically 50 kW or greater) may generate electromagnetic interference (EMI) with electrical systems. Early indications can be considerable radio squelch break or static in the intercom system. More severe effects include random illumination of warning lights or erratic engine governor and tachometer operation. In the worst cases, the governor may attempt to fully open or close the throttle.

To minimize the possibility of encountering EMI, do not fly within 1/2 mile of high power broadcast towers.

If EMI is encountered:

• Keep one hand on the throttle and turn governor off or be prepared to override governor if operation is abnormal.
• Monitor instruments carefully, and use cation not to overreact to a false instrument or warning light indication.
• Have electrical system assessed after flight.

SN-36 - Overspeeds During Liftoff

To avoid overspeeds during liftoff:

• Always confirm governor on before increasing RPM above 80%.
• Verify governor stabilizes engine RPM near top of green arc.
• Maintain relaxed grip on throttle allowing governor to control RPM.

SN-37 - Exceeding Operating Limits

Exceeding operating limits causes metal fatigue which will eventually result in sudden failure.

SN-38 - Practice Autorotations Cause Training Accidents

As the aircraft descends through 100 feet AGL, make an immediate power recovery unless all of the following conditions exist:

• Rotor RPM in middle of the green arc.
• Airspeed stabilized between 60 and 70 KIAS.
• A normal rate of descent, usually less than 1500 ft/min.
• Turns completed.

At density altitudes above 4000 feet, increase the decision point to 200 feet AGL or higher.

Practice should be limited to 3 or 4 consecutive autorotations.

Do not roll throttle to full idle. Reduce throttle smoothly for a visible needle split, then hold throttle firmly to override governor.

SN-39 - Unusual Vibrations

If a rotor is smooth after balancing but then goes out of balance again within a few flights, it should be inspected for indications of a fatigue crack.

If main rotor vibration rapidly increases or becomes severe during flight, land immediately. Do not attempt to continue flight.

SN-40 - Post-Crash Fires

Consider fire-retardant Nomex flight suits to reduce likelihood of severe burns.

SN-41 - Pilot Distractions

Reading charts, programming avionics, or attending to passengers are some common distractions that have cause pilots to lose control of the helicopter.

When hovering, keep both hands on the controls. If tuning a radio or other task is required, first land and reduce collective pitch.

When in forward flight, reduce power, slow down, and frequently look outside.

Never attempt to latch a door when hovering or in flight. It is safer to land first.

SN-42 - Unanticipated Yaw

Robinson tail rotors are designed to have a high level of authority and are unlikely to experience LTE. To avoid unanticipated yaw, pilots should be aware of conditions that may require large or rapid pedal inputs.

SN-43 - Use Extra Caution During Post-Maintenance Flights

Pilots should conduct a thorough preflight after maintenance has been performed. If possible, speak to the technicians and find out exactly what was done.

After track and balance work, always climb up to the rotor head for a close inspection of the pitch link and control tube fasteners.