Engine ignition use in ice.

[av8r]

"The AFM should have an insert about running the ignition any time there is ice adhering to the spinner, and I've become pretty religious about that as well. Merlins and MU-2s are notorious for flaming out due to ice coming off the spinner, Commanders less so... but still."

Saw the above in a different post and had to comment. AD 86-24-12 was issued to address the very issues being discussed. The AD, which still exist under a different AD number, addresses the mandatory use of ignition during flight operations in the ice environment and has been incorporated in the limitation section of all AFM/POHs. If you are unsure of the specifics please read the information.

[Steve binnette]

I have wondered why we do not have a auto Igntion system?

Other tpe331 airplanes have that setup.

[donv]

Historically, it's because Commanders have not had a big problem with engines flaming out due to ice, as long as the inlet anti ice is turned on before entering icing conditions. Typically, ice shed from the spinners (which is the issue) on a Commander doesn't go into the inlet.

The upside-down 331s (Merlin, Jetstream) have a BIG problem with this, and so does the MU-2, apparently. So the Merlin, for instance, does have an auto-ignition mod (if I remember correctly).

The AD applies to Commanders because the other airplanes had an issue, not because Commanders do.

That said, I do run the ignition with ice accumulation on the spinners, particularly when I know I'm heading into warmer air.

[donv]

A good friend of mine did manage to flame out both engines in a 690 due to ice, but that was because he didn't have the inlet heat turned on.

Something to know, though-- he didn't turn the inlet heat on because it was such a thin layer, and he never visually saw any  ice. So it can take very, very little to flame the engine out if the ignition isn't on.

[Steve binnette]

Interesting information Don.

Thanks

[av8r]

Regarding Auto Ignition: there is a Auto Ignition Kit for the Commanders. Memory says its Custom Kit 138 but that may be incorrect. I will research that and make a correction if it is needed. There are two kits 138 & 139. 138 for 840 and up, 139 for 680T thru 690B.

While the 331 on the Commanders is a solid installation they too are subject to ice ingestion issues. The insidious side of the ice ingestion issue is the ice that is rarely seen and not often considered when ice problems are considered. Ice accumulation in the lower throat of the intake - from the smile back - can be a major player in a flameout. This area is not ice protected "until" the inlet heat is on and if ice accumulates in this area prior to activation of the inlet heat we all need to be very alert and aware of what we are facing. When the inlet heat is activated with ice in the throat area it is possible - and has been noted - that the ice will lose adhesion and dislodge as a full sheet which may result in airflow disruption or blockage and flameout.

[donv]

av8r-- absolutely. However, Merlins can flame out even with the inlet heat on. That's the difference. A Commander is unlikely to flame out if the inlet heat was turned on before encountering ice.

What you described is very likely what happened to my unfortunate friend... and I note, he never saw any ice accumulate visually.

[Bruce Byerly]

I have wondered why we do not have a auto Igntion system?

Other tpe331 airplanes have that setup.

Steve,  auto ignition is available.  But, why pay extra for "auto" when you already have "instant" as long as you remember to turn it on?   

[donv]

I do always turn the ignition on before turning the inlet anti ice on. If everything is okay after a minute or so, I turn the ignition off (unless I see a substantial amount of ice accumulating).

[Bruce Byerly]

And just to clarify, by "instant," I mean if you are flying with the ignition "on," it doesn't need to react to negative torque or a flameout to fire, it's already "on."  The operation of the plane would not change whether the auto option was installed or not. 

I'm not sure how long ignitors last, but I really don't think it's even worth considering.  I'm not shy about leaving them on anytime the inlet heat is on i.e. visible moisture under 10C.  Of course discretion is appropriate as there are certainly times when things are stable, ice free, and you may choose not to have the plane in full combat mode. 

[donv]

As I mentioned, I run the ignition a lot as well, although probably a bit less than the official recommendation. I do run ignition for every takeoff and landing, though.

I had to replace a couple of ignitors at the last 150 hour, although looking back at my records, I think this was the result of a 300 hour ignitor check.

[donv]

Interestingly enough, at my last 150 hour they commented that my ignitors looked pretty good. Apparently they've been replacing a lot of them on their 690s lately.

I was a little bit surprised, to be honest, since I not only run them frequently in icing (when ice is visible on the spinners), but also for every takeoff and landing as a general precaution.