Lr 45 ?

[TRBojet]

For operators of the Lear 45: Any problems starting the engines on battery power in cold weather? I just went through training and they mentioned that Bombardier doesn't guarantee engine starts on batt power in temps less than 0C. We looked into adding an APU into ours but will be too expensive at this point. Any ideas on the cost of the Keith A/C and how that works for pre-cool/heating of the cabin?

Thanks.

 

[hiflyer731]

It's "Not Recommended" to start engines on battery power at or below 0C. We have an APU so it hasn't been much of an issue except if the Emer Batt is a little weak it will draw down the voltage and sometimes even shed some avionics during a start if you leave the avionics masters on. Just be sure you have a GPU available or a heated hangar you can put the plane in for a few hours if you are operating in cold weather. From what i've heard the Keith AC does a great job cooling, better than the APU and PACK.

 

[TRBojet]

We have one airport in particular that we go to that doesn't have a hangar (unless we build one), doesn't have a GPU (unless we buy one), self-service fuel, no de-icing... Unfortunately, it's one of our frequent stops so the owners would actually consider buying a GPU for us to keep at that airport. Maybe for the 12-15K it would be worth it.

 

[hiflyer731]

I don't know the reasons why there are issues with a cold start but i suspect it is the cold soaked batteries. If that truly is the case maybe a heater that could blow hot air into the aft avionics bay to preheat the main batteries would work and be cheaper than buying a GPU.

 

[SDCFI]

We have the freon air/aux heat on our 40's at Flexjet, not sure of the manufacturer or cost. The a/c is better than the APU for cooling but the APU wins hands down when it comes to heating. There are two fans, one up front for the pilots and one in the lav area that blows air up and forward. The a/c will blow cold air front and back but the aux heat only comes from the rear so you get almost no heat up front until the entire cabin warms up. Also, you need both gens online for the a/c compressor to run, AND you only get aux heat with ground power, it won't run with a generator on but if you've got an engine running you can at least have the pack on and get some heat.

Any battery will put out less amps in cold weather. Bombardier also says if you can't preheat or get a GPU you can pull the batterys out and store them inside. That may be more of a maint function but may be an option for you.

 

[LJ45]

The cold starting limit is a TFE731 thing, it takes a lot to move that cold gear box oil for the fan when it's below 0. you should have a GPU or APU below 0 c.

 

[TRBojet]

Thanks for all the responses. When I flew the LR35 I don't remember having any issues with battery starts in cold wx. If it's a 731 thing maybe we'll be OK. I am going to look into getting a rectifier for that airport. That might be easier to maintain than a real GPU.

 

[CDogg]

Can't you justify a few hundred or even thousand dollars for some simple ground support equipment... Isn't a starter/gen alone in the $3,500-3,800 range? If the boss can afford a multimillion dollar jet surely he could afford to buy a used GPU for that airport you operate in and out of often.