Turbofans in cold

[Maynard]

Can someone explain why turbofan engines are never tented day or overnight in -40 etc etc, but turboprops are(for some companies)? What exactly is the difference?

[Troubleshot]

Turbofan fan blades (N1) is where the real damage can occur from chunks of ice (or even hard snow) getting sucked in, also prevention of free rotation of the fan blades due to freezing of blades to the inlets can cause a hung start or worse, engine stalling. Most Turbo fans have an operational oil temp limitation of -40c to-50c so trying to "tent in" engine heat is not required but it is helpful as per the MM. If a turbo fan is not going to be running for a while or is operating in prime icing conditions ice can form on the inlet guide vanes, then in can break free and do some serious damage to compressor blades at high power, that's why you see some operators do run-ups before take-off.

The main reason you don't see covers on WestJet, AC, Transat, Sunwing, etc... most of the time is that they are simply not on the ground long enough to bother with unless there is some major weather coming.

So I guess if there is no precipitation coming it is not required.

[Maynard]

Can you explain what advantage there is to tenting a pt6 overnight in -40 weather?

[Troubleshot]

I would assume it is to keep the oil warm and snow/ice out , the exhaust/turbine section is somewhat exposed on the PT6 and filling it with ice would be bad. I have worked on the PT6 but I know there are guys here that know way more about this engine and may have a better answer.

[Ballsssssss]

The engine tent/blanket/cover is to keep the heat from the tanis heaters, or whatever engine compartment heaters one is using, inside the engine. The aluminum that airplanes are constructed of conducts heat easily.

[reign16]

hello i am new here in your forum...



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blanchard grinding

[DHC3Rwannafly]

Great...I'm super pumped you teased me into thinking I got an intelligent response to my question....

[MZUNGO]

because a prop has rubber seals in the hub and gearbox where parts have to move. like the prop shaft and blades. a turbo fan usually has labrynth seals for its moving parts, so they are not as affected by cold temps as a PT-6 might be
M

[Maynard]

If there is no heater inside the cowling, is there any point to tent a pt6 overnight in the cold?

[dashx]

There is an STC out there for a heater system for PT6's. Years ago I had it on file for Dash 7's. If memory serves me correct it was designed to keep the oil warm. Aviall might carry them and the same company has STC's for other A/C. In any case they were about 3K US years ago per engine so the owner said no......

Air Tindi had a system on one of their previous Dash 7's (S/N 072) which they sold. Each nacelle had a twist lock plug permanently mounted. When I saw it the wiring (and the systems) had already been removed. This had to be a 110v system.

But i guess now they have a hangar up there for the 7's..............

I used the cheap ceramic 110V (cubes) heaters when I was up north. They would last at least one winter. Each heater had its own plug and circuit breaker. Because each heater used almost 15A. We never tented the engines but did use the herman nelson in the morning. When it got -40C the oil temp stayed at 0C. Normally it was enough to start. If the engine was not in "good" shape you needed the herman nelson.

[brownbear]

PT6 engines tents help prevent loss of heat from the tanis heaters, or car warmers. I used both.

The STC is 2000 bucks. See Tanis products for the pads and stc. You can order direct from them. It works nice. If tented in -20 you will be plus 20 or so on the oil temp. Which means happy seals.