Fuel control Unit - Warning
feel free to contact us ms@robinsonhelicopters.org

 

Barney
Member Since : 2008
Posts(19)
--

Fuel control Unit - Warning

07-13-2014 01:28:21

.This AD has just been released by the New Zealand CAA. Obviously the problem won't be limited to machines here. Seems odd that they want the FCU pulled apart every 200 hours - you would think that it should be possible for the manufacturer to supply washers that wont break up !

Take care ! Vance

Airworthiness Directive ? Robinson R44 II Helicopters
This AD is prompted by an incident reported to the CAA of a loss of engine power on a Robinson R44
II which resulted in the pilot carrying out a successful auto-rotation landing. A subsequent
examination of the FCU revealed material disintegration from washer P/N 367757 which was ingested
through the fuel system and resulted in a loss of engine power. The material found was similar in
appearance to Polytetrafluoroethylene (PTFE) thread-tape. A laboratory analysis determined that the
composition of the material as PTFE, a thermoplastic polymer associated with washer P/N 367757.
This washer is fitted to the fuel cylinder injector in the FCU. Since this incident the CAA has been
advised of a further 15 defects associated with the FCU washer.
DCA/MA/17 Fuel Control Unit RSA-10AD1 ? Inspection
Applicability: Precision RSA-10AD1 Fuel Control Units (FCUs) installed on Robinson R44 II
helicopters fitted with a Lycoming IO-540 series engine.
Requirement: To prevent restricted fuel flow and possible loss of engine performance caused by the
breakdown of washer P/N 367757, accomplish the following:
Remove the FCU from the aircraft and inspect the idle valve shaft thrust washer P/N
367757 for defects. Disassembly of the FCU is required which can only be
accomplished by an overhaul facility. If any defects are found, rectify before further
flight.
(Occurrence 14/793 refers)
Compliance: At 200 hours TTIS or within the next 5 hours TIS, whichever is the later, unless
already accomplished within the last 200 hours TIS. Thereafter inspect at intervals
not to exceed 200 hours TIS.
If reduced engine performance or a stiff throttle is experienced, accomplish this AD
before further flight.
Effective Date: 11 July 2014

Replies

Barney
Member Since : 2008
Posts(19)
--
07-21-2014 08:22:08
Just had my unit inspected, machine has flown 1200 hours. The offending washer was shedding small pieces of plastic from the friction surface.

The engineers says that so far all FCU's examined so far have had washers disintegrating to some extent.

Fortunately most of the debris is small and probably passes through the injectors !

Hopefully a solution will be found.

Vance