Page 58 - Volume 14 Number 4

TECHNICALLY SPEAKING
Prepping your Airplane for a Trip
by PAUL JENSEN
Getting ready for a long cross-country trip? Worried about things that can go wrong? If so, this is a short list of simple checks that an owner can do that might prevent an AOG (aircraft on ground) event. All that is required are a few inexpensive tools and an hour at the hangar.
One of the most common events is a flat tire. Usually most flats happen when the tire is underinflated. Pressing hard on the brakes during a landing rollout is when this typically happens. My guess is the tire turns but the wheel does not, which shears off the tire stem.
Because it is so difficult to check the tire pressure on a Cirrus, many owners don’t check it often enough. It needs to be done every two to three months. Sometimes I will see a drop of 5 psi in the tire pressure between checks when the outside temperature has been consistent. When there’s been a drop in temperature of 40 degrees or more, I’ve seen the tire pressure drop as much as 10 psi.
To make it easier to add air and check tire pressure, I use an angled tire chuck with a pressure gauge built in (see Figure 1). After removing the round plastic insert, pull the airplane forward until you see the tire stem. Remove the cap and place the angled chuck on the tire stem and push hard. The tire pressure should be visible. If it is low, press the lever to add more air. Check your Pilot’s Operating Handbook (POH) for correct tire pressures.
Figure 1: An angled tire chuck with a pressure gauge built in, makes it easier to add air and check the pressure.
Speaking of flat tires, it is important to use the right tools to jack up the plane. Many mechanics are not familiar with the Cirrus and will use a single wing jack. This is only OK if two are used – one under each wing. To begin, the tie-down ring is removed and a jack point is screwed in. Each jack would need to be raised the same distance, at the same time.
With a single jack lifting the wing, the jack can slip off and punch through the wing. This is a $40K mistake. If this happens, your airplane will need Cirrus engineering involved to get the wing repaired correctly.
To avoid this drama, carry a jack pad in the baggage compartment. It inserts into the wheel assembly and then any floor jack can be used to raise the tire off the ground. Figure 2 (on opposite page) shows a jack pad inserted in a wheel. The jack will push up on the jack pad allowing the wheel to be removed from the other side. Note that the white line on the tire is used to line up the tire stem to the wheel pant access hole before airing up the tire.
The next problem is a dead battery. You go out to your plane, turn on the switches and attempt to start it. You hear a click, click and the propeller just sits there. Your trip will be delayed.
Do not jump-start the airplane, you can damage the avionics. Jump-starts have damaged the Avidyne Sensor Interface Unit (cost $3,000). As the POH says, remove the
56 ■ COPA Pilot
MAY 2019