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R44 Raven II Hot Starts

A definitive statement.

One of the perpetual discussions amongst R44 pilots (or at least those I talk to) is how awkward the Raven II can be to start if has been recently shut down – referred to as a “hot start”.  Most R44 pilots have come from the R22, which does not have a fuel injected variant; so the starting procedure is somewhat different (although the R44 Raven is the same) – and even following the procedure in the Pilots Operating Handbook will not always result in an easy start if the machine has recently been shut down.

Doing a quick search on Google for the problem results in at least 5 different starting scenario’s, all different – yet all are claimed to be successful.  The thing is you have to be very careful when dealing with failed starting attempts because if you are not then you will end up damaging the starter ring gear – to which end the aircraft I use has the following terms in its Self Fly Hire Agreement:

To protect the R44 starter ring-gear from damage on engagement due to rotation of the starter motor gear, the pilot will wait a minimum of 10 seconds after any attempted engine start before attempting to start the engine again. After 3 failed starts, the pilot will wait a minimum of 3 minutes for the starter motor to cool before attempting a restart.

The PoH even has starting tips; but none of them deal with the specific situation of a hot start.  Well, in this quarters Robinson News (a four page flyer sent to Robinson owners / safety course attendees worldwide), RHC have finally addressed the issue.  Of course, anything printed from RHC is classed as a definitive statement!

It turns out that the poor hot start performance of the Raven 2 is caused, typically, by the fact the resultant heat in the engine compartment causes fuel in the fuel lines to vapourize – and thus there is none to start the engine with again.  Robinsons advice for improved hot starts is:

Pull the mixture control knob full out.

With master switch on, activate the aux fuel pump by turning key to “prime” for 20-30 seconds.

Then proceed with normal start.

Their reasoning for the prime with the mixture out (and thus not really priming) is that since the mixture is at idle cutoff the aux fuel pump will draw cooler fuel from the main fuel tank and pump the hot fuel in the lines through the fuel return line back into the fuel tank instead of the engine.  A scan of RHC’s actual advice is here.

It makes sense when you think about it – hope this helps fellow pilots who’ve had trouble hot starting Raven IIs, especially in hotter climates than the sunny United Kingdom!

3 thoughts to “R44 Raven II Hot Starts”

  1. I’ve had this problem — and believe me, where I fly in Arizona, it’s HOT. The technique that works for me is to push the mixture full IN, skip the priming, and crank the starter. The engine catches immediately. This works for me, but I only use it if the engine is very hot — in other words, I’ve shut it down less than 5 minutes before and it’s a hot day.

    Didn’t realize Robinson had official advice — this must be new. I’ll try that next time.

  2. Wish I’d read this advice before last weekend. Flew in to Leicester to meet a friend who also arrived in an R44 Raven II.

    We talked about hot start problems up in the bar, then went back to our R44s at the same time. He had lifted and departed before I managed to get the engine to start!

    Will definitely try this next time; thanks!

  3. Like everyone, I’ve had the same problem. On one of our Raven II, if the aircraft was warm you did not have to prime at all, however on the Clippers we have now, I find that we have to prime regardless.
    When the aircraft is warm, I prime, then push the mixture in very very slowly, when the engine catches or attempts to fire I release the starter immediately and then continue pushing in the mixture very very slowly. The key is in letting go of the starter button at the right time.

    After three failed attempts, the POH says to allow starter to cool for ten minutes.

    Good article, it took many failed attempts to come up with a way that works. Any helpful advice is always welcomed. Thanks!!

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