Cold, Hard Prep

Getting your airplane, your skills and your judgment tuned up for winter flight takes extraordinary attention to detail


By Bruce Chien

Wintertime is just around the corner. In the Midwest, this means gray, cold, wet, windy and only rarely clear and cold. It means IMC, wind and ice. Its time to prepare both pilot and aircraft.

Once the weather is cold, the usual precautions apply. Starting cold engines below 32 degrees F is an invitation to not make TBO. All the oil has drained off your camshaft since that last flight two weeks ago. That thick gooey stuff just doesnt push well through the impeller until it thins a bit. In the extreme case, the barrels get hot, and the cold oil doesnt mobilize until there is irreparable damage to the hot section.

Simply do not allow this. There are many, many ways to warm your engine; many Alaskan operators take the oil in at night. Yes, you read that correctly. They drain the oil into jugs, keep it inside where its warm, then pour it back into the engine when its time to fly.

You can also heat the oil while its still in the engine, but that takes wattage and patience. The tools run the gamut from the Northern Companion stove, which is little more than a white fuel burner vented to your cowl flap outlet, to various electrical heaters.

Flyers on a budget beware, however, that if you set up a temperature gradient between the pan and the barrels, moisture in the oil may condense in cool reaches of the engine, setting up corrosion. Dipstick heaters may warm a little part of the oil puddle, leave the barrels cold, and leave thick oil at the oil pickup.

Therefore, its best to heat both the pan and the barrels. The oil should be runny and the barrels slightly warm to the touch.

If you dont have the watts then you also need an engine cowl blanket. You need whatever it takes. When were skiing in the back country, we carry a two-stroke Coleman 1000-watt generator. Its just enough to power the two oil pan heaters and the twelve barrel heaters. Itll also produce 12 volts if needed.

Then theres the cabin. Preheat the cabin, but not with carbon monoxide and soot-containing burner blast. Use an electric heater if possible.

Cabin preheat is more than a luxury. Its easier on your gyros and your transponder will work forthwith. Just because its winter doesnt win you a class C transponder exemption.

Do This Now to the Airplane
The important thing to do now is to prepare for those cold months ahead. One primary task for cold-weather operations is to inspect the cabin heat. It makes sense to annual the aircraft in the fall. That way the exhaust heater muffs get pressure checked just before their value goes from nice to essential.

The Janitrol heater in the twins tailcone gets a pressure check as well. Every winter there are a dozen episodes of carbon monoxide poisoning. Dont be one of them.

Theres pitot heat. Do more than just turn it on and watch the ammeter. Many systems have two elements in parallel. One element can burn out. If it does, youll still get ammeter drop but the pitot will still freeze in the extreme cold. Turn it on and go touch the pitot. It should get hot, not just warm.

If you have known ice gear, its time to get the brushes checked on the hot props, the hot plate heat verified and the boots inflated.

Its TKS pump check time, too. Theres nothing like a disconnected glycol hose to really change your attitude during a flight, and no time like when on the ground to check your gear. One thing you want to avoid is the awful realization when in the clag that only one wing or one propeller has shed its ice.

Dont forget the fuel system, either. Remove any trace of moisture immediately – before it gets cold. It simply turns to ice in the flight levels now and will do so at lower altitudes in the weeks to come. This is particularly important in airplanes with fuel bladders, as they have more of a tendency to retain water. Inspect and reseal fuel filler caps as well.

It is not OK to have a bit of moisture in the bottom of the gascolator or in the crossfeed lines, so drain them, too. Top off with fresh fuel. Aromatics, which help give the fuel its vapor pressure, vent off with time. Ice-cold fuel has a hard enough time creating vapor without being stale to boot.

How about that vacuum pump? How old is it? 400 hours? 700 hours? 1200 hours? Do you have working backup? If you do not, perhaps a scheduled replacement would be in order. If it goes belly up at the wrong time, that $400 would look like a real bargain.

Electric AIs and backup vac systems have been the norm for a while. This includes electric standby vac pumps and even the lowly Precise Flight manifold vacuum, which taps vacuum from the airplanes induction system. Now, however, there are other choices with the development of portable electronic heading and attitude systems on the market. They are at the brink of affordability and probably warrant consideration.

These include systems by PC Flightsystems and Control Vision that turn an IPAQ personal digital assistant into a mini-electronic flight information system, complete with solid state attitude indicator, moving map and even terrain warning and real-time weather.

In addition to backing up the vac system, they can also ensure you dont lose everything if the electrical system takes a dive. Speaking of the electricals, hows your battery?

Theres nothing more disappointing than a lack of cranking – except maybe losing an alternator in flight and discovering then that the battery doesnt have enough charge to keep the radios going.

Heres a trick the Army uses: Pulsing desulfators. As lead acid batteries age and cycle, the lead plates become encrusted with lead sulfate crystals. As the plates get encrusted, storage capacity erodes and cold cranking reserve takes a plunge.

When the tanks at Fort Hood are connected to these devices continuously, almost all the tanks will start, even after sitting for a season. When they are not connected, the start rate is about 25 percent. I have an old battery that sits on such a device. I removed the battery from the airplane after four years just on principle – and that was four years ago.

Last summer a friends Piper Arrow wouldnt crank, so we took a shot and put in this eight-year-old battery. It turned his engine over and over, and off he roared. You can buy one of these devices, if you shop carefully, for 50 bucks.

If you have no hangar or no electricity, solar versions are available. Put the Solar Plate on your glare shield, run the wires to the battery. This works great if the battery is accessible in the cabin, but even if its not you can run the wires through the lower door seal without causing any problems.

Wintertime flying also means trying to get on top. Have you checked your waste gate for 75 percent critical power at the 75 percent critical altitude lately? The time to discover an exhaust leak or a bad header gasket is now, not when you lose turbo boost and need to head back down ice-laden clouds.

Make sure also that your cooling baffles are in order. Cooling baffles in winter? Trying to climb out of an ice layer at max power is a time of high thermal load on the engine(s). If it overheats, you dont make it on top before the wing degrades to the extent that no amount of power will do the job.

As long as youre thinking about flying high, check the oxygen system. Its a bummer to have to descend back into the ice because youre out of oxygen, and even worse if you stay up there and suffer from hypoxia. Check out that cylinder. Make sure its been inspected in the last 10 years if its steel and within the last five if its almuminum. Nobody will refill it if it isnt, and on the road is no time to find that out.

Next check out the exterior of the airframe. Hydraulic landing gear struts sit lower in the winter – are your struts up to snuff? Get them serviced, get the leaks stopped and add moisture-free nitrogen so you wont have ice crystals etching the barrels.

Other things to check include your your alternate static system, pitot drain and manifold pressure line drains, if applicable.

OK. That was a lot of stuff. Your aircraft is ready. Are you?

Do This for Yourself
Prepare your piloting skills and ready yourself for the judgment calls youll be expected to make.

The first step should almost certainly be a fall instrument proficiency check. Review your logbook and see when the last time was you really had to make it in through the clag. Ensure you are not just book current, but also proficient.

Consider flight planning. There will almost always be a 30-knot wind from the northwest, which will throw your experience with fuel planning into disarray. In the lower flight levels the headwind can run to 90 knots if youre going in the wrong direction.

Some destinations will only have an ILS in the downwind direction. Whens the last time you flew a downwind ILS, without a circle to land, because it was 300-1? Do you really want to circle to land even in 600-2 with trace ice left on your wings? Whens the last time you rehearsed the downwind ILS variant?

Next, take a look at your usual wintertime trips and evaluate the short stops you may encounter.

Going from the Midwest to the Front Range means a stop at North Platte or Hastings, Neb. Both have good FBO support for wintertime ops. But if the wind is really howling, how about something closer in yet, say Lincoln, Neb.?

Before you launch, however, call ahead. Remember that the size of the base is not necessarily an indication of the facilities available when you get there.

Three years ago I made a precautionary fuel stop at Centennial Airport in Denver, only to find it was snowing at 32 degrees F and the flakes were sticking to the wings. After fueling, I needed glycol, but both of the trucks on the base – one at each of two FBOs – were out of commission.

The only option for deicing was going into a warm hangar, but then Id just have to climb again into freezing moisture, so that was not a good option. It was off to the Holiday Inn for us because of bad PIC planning.

Carefully consider your missions before you plan on winter flight. Are you really going to cross the Great Lakes in the winter, even in a twin? There have been a few cases of twin pilots who went down after their crankcase breather tubes iced up and the pressure blew out the seals, dumping the oil overboard. Wintertime ops in areas of high moisture can be deadly, even with ice protection gear.

Perhaps its time to review your personal limitations and tolerance for risk. Dealing with unfriendly terrain and icing conditions are somewhat easier if you go high, away from all the moisture. Did I mention oxygen?

Finally, after all the preparation is said and done, consider what is on your wintertime survival list. The obligatory blankets come in handy in the back seat, of course, but youll also want to have a heavy jacket and gloves ready for the PIC. Even with the interior toasty warm, a door coming open can incapacitate you in 10 minutes in the cold. Put a pair of gloves under the seat.

Consider the possibility of a forced landing, whether due to mechanical problem, icing or other factors. In the summertime, forced landings can simply be a major inconvenience, assuming you have water on board. In the wintertime, in the Rockies, the upper Midwest or the plains, hypothermia is the killer.

Be prepared. Maybe its time to think about a 406 MHz personal locator beacon. At the very least, file IFR when possible so that your search and rescue time has a shot at being less than two days.

When planning your stops, think about whether preheat is available at your stop. Are you on your own? How about cowl plugs and a blanket?

By now, youre probably thinking, This guy had been chewing my ear for the last 10 minutes and there are more than fifteen items on the list. Maybe I just wont go.

And, that may be the best choice. But, with a systematic approach, you just may have it covered.

Oh, and did I mention that chronically leaking door seal that your spouse always complains about and stuffs with the blanket?

Also With This Article
Click here to view “Personal Beacons.”

-Bruce Chien is a CFII, AME and owner of a de-iced Piper Seneca II he routinely flies to ski destinations.


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