Cold Weather Operations

[Ryan Smith]

Hi guys,

So the woman that owns my family's airplane is an FAA Designated Pilot Examiner and has a couple of check rides scheduled for Friday that are well outside of reasonable driving distance to fit into a day. Her Baron is in the shop in the middle of a pretty extensive annual to include some cylinder work to try to get a few more months out of the engine before it's replaced. That leaves her with taking the 170, and she's simply not comfortable in the airplane, and has asked me to chauffeur her to her check rides. Of course I couldn't say no, so I'm getting myself and the airplane prepared for an early morning departure on Friday.

The issue that I had not considered is how cold it's going to be at 6AM when I'm trying to get the airplane ready- it's forecast to be down below 20° at that time. I don't recall having flown the airplane in weather that cold before so I'm reaching out for some advice. The airplane is in a tee hangar without a door, I do not have winterization plates, and so far as I know, there is no preheater for the airplane. Putting it in a heated hangar is not an option, so I'm stuck with what I have.

My questions are:

1. Short of pulling the prop through by hand thoroughly, is there anything else I can/should do with cold oil?
2. Do I need to check the oil the day before? It's got less than 10 hours on an oil change, I believe it was single-weight Aeroshell 100.
3. How much prime should the airplane require?
4. What will be the impact of having open cowling grilles with nothing to partially block airflow? Our flight plan will have us making our first leg at 5,500ft so that will make ambient air temperature in the single digits.

I can see if Zenda somehow has winterization plates for the cowling since the airplane lived for four years in Buffalo, NY (but since I flew 40 hours in the four years it was gone, I somehow doubt that it saw much time in the cold air).

Any other words of advice? I'm excited as I can be. I used to fly her late husband around to check rides when I was a kid (12-14), so my life seems to be rocketing backwards right now. It is 2015, and I did frequent upon a Delorean when I was living in Illinois, so maybe there is something more subversive going on.

I appreciate any words of advice, even if I am overthinking things. I just want to take care of the old girl (the 170, not Zenda. She can fend for herself). As most can tell on here that have read my posts, I'm crazy about the airplane and just want to ensure that I'm not damaging anything.

Best regards,

Ryan

[jwmcgu]

Ryan,
I prime mine about 4 or 5 times in the winter. It may differ from plane to plane. Being that cold be sure you have a strong battery. Check the weather * check the weather and then check it again.
Met you at Triple Tree this past year.
John McGuire

[bagarre]

When I used to fly in really cold (15 degree mornings) weather, I'd pull the prop thru a half dozen times to get the oil moving some.
I'd prime 6 or so shot (short stroke primer) and leave the primer pulled out. That way I could give it an extra squirt if it started to konk out.
Pump the throttle twice for good luck

After that, she'd fire on the second blade and I could keep it running with the primer until it could run by itself.
If it died, I'd give it 3 more squirts of primer before re-starting.

Nowadays, I don't fly if it's below 40 so there aren't any special procedures.

Not using the cold are baffle kits will just mean your oil temps will run low but still well in the green.

Best of luck!!

[pdb]

Ryan...You can use the primer enough to get it going when its 20° (use the carb heat too until it starts and runs smoothly), and keep a fire extinguisher handy as well, but do you really want to do this?

The problem with cold starts is not getting it started, its the wear that occurs in the first few 20 or 30 seconds of operation, which is astounding. You have metal to metal contact in the bowels of the engine until the oil starts flowing and you can develop an oil film between the moving metal parts. The wear you experience in this time period is equivalent to many, many hours of normal operation.

There is really no substitute for preheat in this condition. Not only do you need the oil warm enough to flow but you need to get the rest of the engine warm too. You have an engine with steel, aluminium, and other metals which expand at different rates when warmed that were designed to work best and fit well at normal operating temperature. Things, especially cylinders, are too tight when cold.

If you need to do this on a one off basis, get an old blanket and a 100W bulb. Put bulb in at the bottom of the cowl, plug it in, and wrap the engine in an old blanket secured by bungees. Keep it on all night before you fly. This is not optimal but its sure better than no preheat. The engine compartment doesn't have to be a toasty 70° but it should be above 32° and warmer is better.

[GAHorn]

I pretty much do what David just posted, except I do not recommend pumping the throttle. Here's why: Pumping the throttle activates the accelerator pump in the carburetor. (This sprays a shot of fuel into the carb throat.....where...since the engine is not running..it promptly runs back downhill into the air box where a simple backfire can ignite an intake fire. You cannot easily detect that in the cockpit and no one is likely standing around with a fire extinguisher nor would they likely know what to do anyway with you swinging a prop.)

If you can place an old blanket or sleeping bag over the cowl and block the inlets, and put a force-air-heater of some sort (like a bathroom or milkhouse heater) to direct hot air up into the cowling lower exit overnight before the flight... that'll likely help it fire right up without any special treatment at all.

But lacking any type of preheat... Like David said, prime it 5 or 6 shots and pull the primer out again to load it with fuel...crank the engine and when she fires...slowly push the primer IN to keep it running, and quickly re-load the primer again for another shot if you should need it.
Once she runs steadily for 30-secs or so she should keep running just fine. The first few minutes running with carb heat will help it start-up and keep running...but DON"T FORGET to remove the carb heat for takeoff.

Be aware that with 100W oil ....the oil pressure will be slow to rise...it may take a minute or two just to get any indication at all, so don't rev up that engine until she's idling smooth for several minutes and then limit the RPM below 1000 until she's been running at least 5 minutes. You should be good to go after that.
Don't be too concerned about winterization plates and don't jury-rig anything in that regard. It'll be just fine, but as has already been said, the oil temps will likely remain lower than usual, but it shouldn't harm a thing.

Keep your eye out for carb ice if you get into a temperature inversion at altitude.

[flyboy122]

Straight 50 wt oil is really thick for a cold start. You probably should consider some kind of preheat. The lightbulb trick kinda works, but you need good insulation. If you can beg/borrow/steal a torpedo heater, that will make short work of it.

Once its started and warmed up the engine won't care how cold the ambient air is. You, on the other hand, will become quite cognizant of any air leaks around the doors and windows!

DEM

[Ryan Smith]

Straight 50 wt oil is really thick for a cold start. You probably should consider some kind of preheat. The lightbulb trick kinda works, but you need good insulation. If you can beg/borrow/steal a torpedo heater, that will make short work of it.

Once its started and warmed up the engine won't care how cold the ambient air is. You, on the other hand, will become quite cognizant of any air leaks around the doors and windows!

DEM

I flew the airplane for an hour at night a couple of weeks ago. It wasn't frigid, but it was pretty chilly, and I realized then why Cessna redesigned the cabin heating system in 1953.

Thanks for the replies, everyone. I feel a lot more comfortable now, but I will see what I can scrounge up the way of a method of preheating. The only fire I'm interested in experiencing is the one INSIDE the engine.

[4-Shipp]

Tape over the air inlets on the leading edge wing roots with duct tape. Otherwise the vents will blow open and you will not be happy...trust me on this one.

[GAHorn]

Overhaul your fresh air vent cans as described in the 170 News and elsewhere and they won't blow open.

Here's a link where overhauling them was described: http://www.cessna170.org/forums/viewtop ... =air+vents

[DaveF]

If you can't get any preheat, how about flying the airplane the day before, when it's 45 degrees? After flying, wrap the cowl with lots of insulation. There might be some residual warmth the next morning. At the very least things will still be well oiled inside.

[blueldr]

Also keep in mind that the congealed oil in the oil pressure line may make he indication very sluggish. Any available cockpit heat will help that too.

[jrenwick]

I never had winterization plates for my 170, so I put duct tape over the part of the cooling intakes where the winterization plates would have been. That worked fine to keep the oil temperature a little warmer than it would have been without it. I always removed the duct tape post-flight while the adhesive was still fresh, and cleaned up the residue with mineral spirits. That way the tape didn't damage the paint.

[bagarre]

I flew the airplane for an hour at night a couple of weeks ago. It wasn't frigid, but it was pretty chilly, and I realized then why Cessna redesigned the cabin heating system in 1953.

Thanks for the replies, everyone. I feel a lot more comfortable now, but I will see what I can scrounge up the way of a method of preheating. The only fire I'm interested in experiencing is the one INSIDE the engine.

The old heater can be improved by adding a diffuser across the firewall. There is a fair amount if heat buy 90% of it goes up behind the panel after roasting your left pinky toe. The diffuser helps spread the heat around.

[Kyle Wolfe]

Just went for a flight tonight with new member 1692D (Tony). It was 10 degrees.

I agree with what's said already. Preheat somehow! The light bulb, milk house heater, blanket all help. Everybody has their approach. I have a oil sump pad heater but also use a Kennon cover with a milk house heater also blowing through dryer vent ducting into the lower cowl. I also plug a ceramic into the cockpit to warm gyros plus makes it more comfortable when getting in. With all that I only need to prime twice to fire up and almost immediately get oil pressure.

Don't forget to dress warm and keep some blankets or sleeping bags in the a/c too. I hate flying in boots but always wear them in MN winter wx.

Good luck!

[bagarre]

I flew the airplane for an hour at night a couple of weeks ago. It wasn't frigid, but it was pretty chilly, and I realized then why Cessna redesigned the cabin heating system in 1953.

Thanks for the replies, everyone. I feel a lot more comfortable now, but I will see what I can scrounge up the way of a method of preheating. The only fire I'm interested in experiencing is the one INSIDE the engine.

The old heater can be improved by adding a diffuser across the firewall. There is a fair amount if heat buy 90% of it goes up behind the panel after roasting your left pinky toe. The diffuser helps spread the heat around.

http://cessna170.org/forums/viewtopic.php?f=24&t=10951

That's how I solved it.
Required no new holes and bolts over the existing heat valve. minor alteration.