Even though the winter season provides less opportunity for flying due to weather challenges and extended preparation times, the flight training at BFC continues all year round. The aircraft are still regularly maintained despite the need for more defrosting and pre-heating sessions. For those operating private aircraft, they are often stored throughout the winter months and not brought out until spring after an extended period of inactivity. The anticipation to get back into flying as the warmer weather sets in must not overshadow the need for having a closer look at the aircraft immediately after this period of down time. Performing a more detailed and dedicated pre-flight inspection should include a few more key items as identified throughout this article.
Your preparation for the actual flying activity should be preceded by a review of the aircraft technical records. This activity should be used to identify any outstanding or upcoming out-of-phase calendar items that are required for the intended flights. For example, the requirement to have the altimetry system tested and re-certified is every 24 months according to Appendix C of CAR Standard 625. This is also the appropriate time to determine whether there are any Airworthiness Directives (ADs) applicable to the aircraft during its time of inactivity. This may include any new ADs or regular recurring ADs being tracked primarily by calendar time. The spring season has traditionally been a busy time for the maintenance shops who perform many annual inspections in time to start the prime flying season. I often recommend annuals be considered for mid-winter season when the maintainers have more time to focus on the annual rather than blasting through it in spring when everyone else needs attention.
The efficiency of the aircraft battery is often reduced after long periods of dormancy and from the harsh effects of consistently cold temperatures. For those thinking ahead, the aircraft battery and the ELT should also be removed in the fall and stored in a warm dry environment over the winter. This activity alone may very well preserve the life of these batteries while avoiding costly replacement before their expected service life. The aircraft battery itself may or may not prove to be ready for the first flight of the season if its state of charge has already been compromised. The best way to prepare for continued reliability is to still remove the battery at this time and have it serviced, electrolyte levels checked, and trickle charged.
The air pressures in the tires and oleo assemblies may appear to be lower than normal after remaining static for an extended time in cold weather as well. The tire pressures should be adjusted according to the specs given in the POH or Operator’s Manual. Aircraft tires on small aircraft are normally serviced with shop air but be sure to use a good quality tire pressure gauge to ensure the accuracy of the readings. Aircraft tires are tremendously vulnerable to the effects of the weather and direct sunlight causing cracking in the rubber sidewall and tread also known as weather checking. This condition weakens the integrity of the tire not to mention the deep cracks exposing the cord layer of the tire. Extreme weather checking to this degree may require replacement of the tire.
Most light Cessna aircraft have a nose oleo with spring steel main gear whereas most light Pipers and similar low wing types have oleo assemblies in all landing gear positions. The pressure in the landing gear oleos is usually determined by a manufacturer’s spec for inches of exposed chrome - also provided in the manual. It is certainly beneficial to keep the chrome piston section of the oleo clean and dry so that any accumulated debris does not interfere with the sealing properties of the O-rings ultimately leading to premature hydraulic oil (and air) leaks. In fact, a very light film of hydraulic oil should remain on the surface whenever possible to help with sealing and smooth movement when compressed. The oleos are serviced with nitrogen and hydraulic oil but unless you see visible leakage, the oleo can simply be serviced with only air (nitrogen) at this time. Nitrogen is used in preference to shop air since it originates from a cleaner source without moisture which can otherwise internally damage these assemblies over time.
Aircraft control surface hinges may also require re-lubrication which can be determined by simply checking the hinges directly for an obvious presence lubricant. Be sure to check the manufacturer’s lubrication recommendations or consult with your maintenance provider for guidance here. These lubrication requirements may also relate to retractable landing gear assemblies as well depending on the needs of the particular system. Proper lubrication is a small price to pay for continued functioning of essential systems.
In the spring season, birds can be aggressive about building nests anywhere they can find an opening such as in or around parked aircraft. This can surely be a greater concern when parked outside but birds can easily find a home in many T-hangars as well. They are good at finding small openings in aircraft to start nesting such as in the engine cowl inlets (and down in between the cylinders), in the cowl flaps, exhaust or empennage openings or even in the wheel wells of retractable gear aircraft. If you look carefully, you may see bird droppings on or around certain parts of the aircraft as a clue that they are busy building close by. There may be evidence of straw or twigs tucked into the openings mentioned above. If a nest is found, or even the makings of a nest, be sure to remove all nesting materials using gloves and/or a vacuum cleaner to remove all traces of debris. If left in the aircraft, these raw materials could ignite an engine fire or even interfere with control systems.
Always be vigilant during your spring season pre-flight inspections as the birds will take every opportunity to start building nests - even between flights! Have a closer look into the control surfaces, stabilizers and associated lightening holes for evidence of nesting materials. Aircraft normally stored outdoors should be inspected for any damage before preparing for flight. While an enclosed hangar offers greater security from the elements or trespassers, outdoor tie-downs require greater diligence before getting ahead of our safety responsibilities. Even making the time to sit and review aircraft check lists and ensure that all regular flight bag gadgets are available for your convenience.
Perhaps shaking out the piloting cobwebs in spring may be best accomplished through a check out flight with a Flight Instructor or colleague. This is a personal call for private owners who can be honest with themselves and whatever gives them the confidence to fly safely. While many aircraft owners only call upon their local maintenance provider for annual inspections or snags, some may consider having the shop perform a “spring check-up” of the aircraft by going through many of the items mentioned here. Perhaps an oil change can also be performed to rid the engine of accumulated acids and moisture contained within the oil that the engine went into storage with. Discuss your intentions with an AME and remain open to specific guidance on technical matters pertaining to the continued reliability of the aircraft.
A good spring cleaning also works wonders for your aircraft. Spending the time to rinse and detail your aircraft allows you to have a closer look at things and to rid the surfaces of dust and dirt if not stored in a secure clean hangar. Any evidence of that bird poop mentioned earlier should be thoroughly washed away in order to prevent acidic damage to the paint. Clean the windows with an appropriate window cleaner to give you the clearest view possible! For more stubborn stains on the lower engine cowl or aircraft belly (from exhaust or vented oil residue), use a heavy duty citrus cleaner or mild solvent that will not harm the paint yet allow you to scrub those areas until they are clean. You may also want to tidy and groom the aircraft interior as well but remember to be careful around the sensitive avionics screens as they require special cleaners to remove finger prints and the like. If you choose to hire a promising young aviator to wash the aircraft for you, be sure to first check them out on acceptable methods and products used for cleaning. I’ve seen damage caused by the simplest of tasks and a lack of training!
After completing some of these detailed inspections, it is best to fly the aircraft locally before taking off on any trips or lengthy excursions. This allows you as the operator to become aware of any suspect conditions related to the actual aircraft in flight that can then be dealt with before getting too far from home. A test flight can be seen as a valuable exercise in determining whether all of the instrument and navigation systems are working properly. Any bugs or debris in the pitot head could cause erroneous readings on the airspeed indicator in the same way that a plugged static source could also affect the altimeter or vertical speed indicator. Ensure that the cabin vents and heat systems are functioning normally and are also not obstructed for any reason. Check all lights and switches, trim systems and vacuum gyros in flight after giving them a chance to spool up after being in hibernation. This is the best time to discover any little glitches or areas of concern.
So, bringing your aircraft out of hibernation may require a little more patience to ensure that it continues to meet all of its airworthiness requirements. These small aircraft respond best when they are flown regularly. The longer they sit, they also demand more attention and that is just the nature of beast. A good spring cleaning and “tune-up” exercise could go a long way in permitting you more great flying experiences. So consider these spring preparations for a full summer of adventure!