krohmie
Testpilot
Wenn der linke Prop im Wind mitdrehte, also nicht vollständig gefeatherd war,
dann ergeben scih folgende Fragen zur Ursache des nicht Featherns (Ich gehe mal davon aus, das die Cockpit Crew gefeatherd hat):
Wurden, was die Wartung und Prüfung des Feather Mechanismus angeht die Lehren aus dem PH-DDA Unfall gezogen?
Insbesondere: Wurden bei der Unfallmaschine die nötigen Test laut Hamliton Standard SB (Service Bulletin) 657 durchgeführt?
Geklärt werden muss natürlich auch die eigentliche Ursache des Triebwerksausfalls.
Mit freundlichem Gruss
Krohmie
PS: Feathering Test laut SB 657 (aus dem Unfallbericht von PH-DDA):
During ground testing a static full feathering check can be carried out as mentioned in Hamilton Standard SB 657, issued September 1977. The check is carried out with the engine not running. The feathering button is pushed and the propeller should turn to the feathered position. At this position the button should pop out and the propeller should stay in the feathered position. By this procedure the entire feathering system including the pressure cut-out switch is tested. The reason for this SB 657 was "To check the operation of the pressure cut-out switch. Corrosion build up on switch contacts can render the switch inoperative, pressure will continue to increase and will shift the distributor valve which in turn will initiate unfeathering of the propeller. The check should be performed at intervals not exceeding 30 days on operating aircraft."
dann ergeben scih folgende Fragen zur Ursache des nicht Featherns (Ich gehe mal davon aus, das die Cockpit Crew gefeatherd hat):
Wurden, was die Wartung und Prüfung des Feather Mechanismus angeht die Lehren aus dem PH-DDA Unfall gezogen?
Insbesondere: Wurden bei der Unfallmaschine die nötigen Test laut Hamliton Standard SB (Service Bulletin) 657 durchgeführt?
Geklärt werden muss natürlich auch die eigentliche Ursache des Triebwerksausfalls.
Mit freundlichem Gruss
Krohmie
PS: Feathering Test laut SB 657 (aus dem Unfallbericht von PH-DDA):
During ground testing a static full feathering check can be carried out as mentioned in Hamilton Standard SB 657, issued September 1977. The check is carried out with the engine not running. The feathering button is pushed and the propeller should turn to the feathered position. At this position the button should pop out and the propeller should stay in the feathered position. By this procedure the entire feathering system including the pressure cut-out switch is tested. The reason for this SB 657 was "To check the operation of the pressure cut-out switch. Corrosion build up on switch contacts can render the switch inoperative, pressure will continue to increase and will shift the distributor valve which in turn will initiate unfeathering of the propeller. The check should be performed at intervals not exceeding 30 days on operating aircraft."
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