Aircraft Maintenance: Waking from a deep freeze
I recently received an interesting email from an AOPA reader based in Ontario, Canada. He was curious about resurrecting his Cessna 150 that had been stuck outdoors through the freezing Canadian winter as the spring thaw was about to begin. It’s easy to preach about best practices for aircraft storage and maintenance, but I’m keenly aware that the real world often presents us with less-than-ideal situations to deal with.
In this case, the local public airport is left unplowed and basically shut down during the winter. By the time the spring thaw comes for our northern friend, his airplane has been sitting in the cold for nearly six months. While there are a lot of things that can be done to properly prepare an aircraft for this kind of long-term storage, his question was about what he could do now to ease his bird safely back to life.
- Wake up gently.
After sitting so long in a cold-soaked environment, it’s important to get everything warmed up gently before attempting anything. If a heated hangar isn’t available, use a preheater for the entire firewall-forward and a space heater in the cabin for long enough to get everything completely up to room temperature before you so much as move a radio knob or a trim wheel. Every little fragile part has become quite comfortable where you left it last, so get it warm before exercising those parts again.
- Give TLC to the tires and wheels.
If those tires, tubes, and wheels have been sitting in place for months in the cold, they need attention. Jack up the airplane, remove the wheels, and bring them indoors for a thorough brake/wheel inspection and lubrication where the flat spots can begin to relax. Look for weather checking and cracks in the tires and ensure that the tubes are still holding pressure. If you arrived to long-flat tires, I would disassemble the tires and replace the tubes as well. Clean, inspect, and lubricate the bearings and brake components.
- Lube and flush.
Assume that every lubricated joint has dried out over the brutal winter months, especially given the lack of movement. Your aircraft maintenance manual should have a lubrication chart and schedule. Go through it completely for every moving joint on the aircraft. Depending on the amount of time stored, you may need to flush the fuel system as well. However, if the tanks have been left full (and are still full) and you find no significant contaminants when checking the fuel drains, you may be OK. Aviation fuel lasts surprisingly long, but it doesn’t last forever. So, check with your local A&P to decide if your situation requires a fuel system flushing or not. Regardless, you should inspect all the fuel filters and the gascolator. Be sure that temps are above freezing during this work so any water gets removed.
- Charge the battery and conduct a full system check.
Service and charge the battery. Then, go through every system on the aircraft and check its function. That includes every flight control, engine control, electrical system, switch, lever, and dial in the aircraft. If it has stopped working or is about to break with the first pull of the knob, you want to find that out on the ground…not in the air.
- Fire it up, shut it down, and inspect.
Once you’ve preheated, conduct an initial inspection of the firewall-forward, looking for damage from rodents, hose condition, security of all control mechanisms, etc. Then you’re ready to fire up the engine and go through a run-up. It should be a thorough check, including mag check, idle cut-off check, prop check, maximum static RPM check, etc. Once complete, shut everything down and inspect the engine. Look for leaks, pull the plugs, and borescope the cylinders if you have a scope available. Then clean the plugs and reinstall them. Finally, change the oil and filter. The filter should be cut open and inspected.
It would be easy to say that you should simply perform a full annual inspection on an aircraft that has been left dormant over the winter. However, that’s not practical for every owner and not necessary in all cases. If the aircraft was stored in a known airworthy condition and is still in annual, you simply need to do a careful inspection and servicing to ensure that it is still airworthy and safe for flight before going airborne. And, by all means, treat that first flight as all post-maintenance flights should be treated—with great care. Don’t carry passengers and remain within gliding distance of the airport while testing the aircraft to ensure everything is performing properly. Then land, inspect one more time, and you’re ready for your next flying adventure. Until next time, happy flying!
