View Full Version : R44 with EDM-830 shows overhot CHTs
My R44 Raven1 (with 3rd party floats) had a forced landing with 4 POB onto a beach shortly after takeoff from same beach. Next day it was determined that 2 inlet valave had failed. Remaining cylinders were removed and sent to engine shop where they found issues with valve guides in other cylinders. Total time was 285 hours and still 4 months to run on Warranty. However Lycoming are refusing to honour warranty.
At my request a JDI EDM-830 engine monitor was fitted when the six new cylinders were installed. We now have a lot of data on the engine CHT and EGT temps, plus MAPs etc.
The data we have recorded shows that when flying MAPs of 22, 23, 24ins that the CHTs on some cyldinders exceed the max recommended by Lycoming of 435deg F throughout the flight. Yet Lycoming want high MAPs during run-in. From our data this is not possible in our Raven 1. Does anyone else know of an engine monitor fitted to an R44? If so, what CHT temps are they recording?
topendtorque
4th Feb 2012, 07:51
Most unusual your inlet vale, sure it wasn't the exhaust valve? I see Robinson SL 21 re, 'exhaust valves' has been deleted. So whatever that pertained to must now be in the Maint Manual.
In the hotter areas valve guide clearances is something all engineers pay particular attention to. At 285 hours you may have been in front of the first called up valve guide inspection.
Did you mean Number 2 cylinder?
The engine cabinet temperatures are a scary thing in the R44 for sure.
I think it is an area that needs a lot more research work for the hot climes.
tet
The problem we had with the engine failure was definitely inlet valves. However when the other cylinders were inspected they found issues with excessive clearance in exhaust vales. What I omitted to mention was that for the first 73 hours the R44 was (a) hard to start, and (b) always built up a black soot in the exhaust pipe and rear panel of the heli. The carby was re-worked for the starting problem, but from then on the tailpipe was light grey color, and no black build-up on rear panel.
However when we inspected the ports after the engine failure there was a lot of 'soot' in the ports. I believe that this was the original cause of the problem, carbon deposits building up in the ports and on the valves and the high CHT temps baking the carbon so eventually it caused breakdown and failure at the inlet valve sealing surface.
Lycoming want high MAPs for run-in, but this involves higher temperatures than their spec. Following is a sample from 2.2 hr flight in December 2011. MAP 23.3, Cyl 1 459deg F, Cyl 2 405, Cyl 3 453, Cyl 4 454, Cyl 5 458, Cyl 6 430.
The Lycoming manual specs 435 deg F as max long life, but if you fly Cyl 2 for max of 435, the MAP will be too-low for their run-in, and too-low for normal Heli ops. I plan to test this tomorrow 5Feb12.
topendtorque
4th Feb 2012, 09:47
seems strange the thing wasn't run in on an engine test truck with a controlled temperature cabinet.
one or more cylinders could be breathing badly on run in until the rings settle in = high temps all round. your carbon build up theory sounds plausible to a layman.
CaptDean
4th Feb 2012, 15:20
You might want to try the Robinson Helicopters Owners Group web site.
There are lots of Robinson repair facilities folks that hang out on that sight.
I think it is Robinson Helicopters Owners Group (http://www.robinsonhelicopters.org)
Thank you Capt'n Dean, Good suggestion and I will definitely follow up.
I am very keen to find other R44 owners who may be running engine monitors, and observing CHTs in the Raven 1 R44s, as from my data the Lycoming engine cannot run under recommended max temps for normal heli operations.