HYDRAULIC FAILURES AS350B2 AIM -To recognise symptoms of Hydraulic Failure - respond with emergency actions - land safety. RECOGNITION - System Pressure below 30 bars (440 PSI) pilot indications Controls remain powered (Accumulators).
HYDRAULIC FAILURES AS350B2 OBSERVATIONS - Average time required to attain safety speed range (40-60 knots)…Less than 30 seconds from VNE or hover. Hydraulic accumulators charged fully. Hydraulics available through manoeuvres to reach safety speed range. Pre Take Off Checks - Light out 4 seconds. (Ref: RFM Section 8, page 19) Confirm hydraulics failed - HYD light on - pedals firm (Load compensating servo) EMERGENCY ACTIONS - Airspeed - Accumulators - Isolation Hydraulics - Run On Landing.
HYDRAULIC FAILURES AS350B2 AIR EXERCISE - (1) Recognise Hydraulic Failure HYD light on - HORN - Sounds - Pedals Firm - Controls Powered. (2) Airspeed 40 to 60 knots. (3) Select Hydraulic isolation Switch (Collective) OFF (4) Load Feedback 2-3 seconds. Heavier at higher airspeed. Cyclic = 7-12 kgs - left hand load. (Note: Do not push HYD accumulator test depressurise load compensator - T/R controls heavy/flat pitch). Cyclic = 4-5 kgs - FWD load. Collective = Neutral loads - Heavier. Lower Speed. Pedals = Little load at 40-50 knots.
HYDRAULIC FAILURES AS350B2 RECOVERY - (1) Plan a shallow approach to clear flat area. (2) Land into wind with forward run-on landing. (10 knots) - FLAPBACK Do not hover - Refer NTP No. 18 - Helicopter will yaw/drift left. Control forces change/direction intensity. As airspeed slows prior to touchdown control forces can increase. Cyclic = 15 kgs - Left Hand Load Cyclic = 17 kgs - Forward Collective = 20 kgs - Heavier Pedals =Firm - Balanced (3) Shutdown engine holding collective down on Low Pitch Stop. (4) In Hover Hydraulic failure. Land normally (Accumulator Pressure). (Shutdown engine holding collective down on Low Pitch Stop).
HYDRAULIC FAILURES AS350B2 AIRMANSHIP -Refer - (1) RFM Section 3, Supplement 7 and Eurocopter THM Section 8 for Review. (2) AS350B2 - Control forces heavy. Push forward hard to keep speed to touch down. (3) Hydraulics off training AS350B3 - Ensure throttle notch locked + friction.
HYDRAULIC FAILURES AS350B2 THREATS (1)General threats: - weather - traffic (disrupted App and Collision Avoidance) - command gradient (2)Exercise specific threats: - lack of systems knowledge - overshoot briefing and actions ERRORS - Confirmation (double check) of helicopter configuration HYD TEST RESET - Left drift on ground roll (lack of right cyclic offset) - Lack of positive control input - Cyclic FLAT DO NOT ATTEMPT TO HOVER RUN IT ON
HYDRAULIC FAILURES AS350B2 INCIDENT HISTORY (1) 17 July 2007 – AS350 Super D on approach HYD/Horn on due to HYD pump spling failure (2) 9 March 2011 – AS350B2 in cruise experienced HYD/Horn on due to coupling sleeve internal spling failure