PPRuNe Forums - S76 down in Baltic Sea (Now incl NTSB Safety Recommendation)

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- - S76 down in Baltic Sea (Now incl NTSB Safety Recommendation) (https://www.pprune.org/rotorheads/185377-s76-down-baltic-sea-now-incl-ntsb-safety-recommendation.html)

Quote:

"FAR 29 insist that every critical components and critical systems which may have an affect for flight safety must be designed to be failsafe or redundant system."

Just about every helicopter I can think of has a single control input into the main servo, the bolt comes out and that control channel becomes inoperative. I see no redundancy in this.
This includes modern designs such as the AW139.

FAR 29.695 Power boost and power-operated control system.
(a) If a power boost or power-operated control system is used, an alternate system must be immediately available that allows continued safe flight and landing in the event of-
(1) Any single failure in the power portion of the system; or
(2) The failure of all engines.
(b) Each alternate system may be a duplicate power portion or a manually operated mechanical system. The power portion includes the power source (such as hydraulic pumps), and such items as valves, lines, and actuators.
(c) The failure of mechanical parts (such as piston rods and links), and the jamming of power cylinders, must be considered unless they are extremely improbable.

AW139 servo system is designed to release main control valve in case of jam. The first indication will be SERVO 1 or SERVO 2 caution illuminates. It is very important immediately to start monitory Hydraulic temperature on synoptic page (this is not instructed by QRH).
System pressure 3500 PSI is circulating all the time inside affected servo. This constant 3500 PSI flow continuously through the bypass channels begins to rapidly raise the temperature of a hydraulic fluid (expect 1 celsius degree per each 5 seconds). It is expected that quite quickly the hydraulic oil temperature exceeds 134 degrees Celsius and HYD OIL TEMP warning illuminates. Switch off affected system by moving affected SOV to CLOSE on HYD control panel. AW139 has a philosophy where hydraulic SOV switch has switched off the faulty side! AW139 QRH is not clear at all regarding this SERVO and HYD OIL TEMP cautions.
Far out from shore, in the middle of the night, so it is challenging to begin to read and understand what QRH tells you to do and what QRH tells not to do. This scenario should be trained for all crews during recurrent training. It is not so easy even case has been briefed before sim session.

Bristow Lagos and Copterline S76 accidents very similar

The similarity of these two accidents makes very very scared.

Copterline 103, you mean 3000psi, not 3500. Or, to be more in line with the instrumentation, 207 Bar.

Hi,
after following the discussion regarding S76, which went down in Baltic Sea, there seems to be some doubts that some facts maybe has been hidden regarding the facts, that explains what happened.
This is unacceptable. I know how to solve this. Do anyone know the contact information of Jesse Ventura. No questions asked but meny answers will follow. If you have the contact information please write them down in this forum. I will get you the answers.
I think that Copterline 103 has an issues here, because no nobody give us arguments as Copterline 103 if there is no facts behind it, or what do you think?