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Q&A: Pitot Static Checks for a Cherokee 180 & Apache Stabilator Torque Tube Inspection

Q&A: Pitot Static Checks for a Cherokee 180 & Apache Stabilator Torque Tube Inspection

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Q: Hi Steve,

I need more information on what my mechanic calls “pitot static checks.” I ask because he said I need them every two years—but then said only one is needed if I don’t fly IFR.

I am partway through my private pilot training and am using my dad’s Piper Cherokee 180. He said I could fly it as much as I want if I pay for the maintenance and upkeep.

I think it’s great that I get to fly the same airplane every lesson. I started out renting at a flight school and I personally didn’t like when I had to flip-flop between different airplanes. I think it made it harder for me to concentrate fully on the flying part.

But I’m afraid Dad hasn’t kept up with the maintenance on his Cherokee. For instance, the last pitot static check I found in the logbooks was over 10 years ago. I know who was doing his annuals and decided to go to a nearby well-established shop for the first annual I’m paying for.

So far they haven’t found any big-ticket items (whew!) but there have been plenty of catch-up items. I’m okay with that, because I’m going to be loading my family in this airplane and I want to be able to feel like it’s ready.

That’s my story. Now, the pitot static test?

—Learning Larry

A: Dear Larry,

Welcome to the world of flying. I feel like you’ve already made some good decisions regarding your training and the importance of having confidence in the maintenance work done on your airplane.

Unfortunately, there have been and continue to be “soft” annuals performed on a small number of airplanes every year. I’m glad you have resolved to take the steps required to get your dad’s airplane completely airworthy.

The pitot static system check you’re asking about is two separate checks. Both checks are spelled out in FAR Part 91, “General Operating and Flight Rules.”

The first rule is sometimes referred to as the IFR rule. It ensures the altimeter is working correctly and that the automatic altitude reporting system in your airplane is working and within tolerances. If you never fly IFR, you don’t have to keep this one current.

This rule, under FAR 91.411, “Altimeter system and altitude reporting equipment tests and inspections,” says that no one can operate in controlled airspace while operating under IFR unless, within the preceding 24 months, “each static pressure system, each altimeter instrument, and each automatic pressure altitude reporting system has been tested and inspected and found to comply with appendices E and F of part 43 of this chapter.”

I’ll explain a little more about this mandate—but it’s important to realize that even if you’re flying in clear weather, this inspection must be current if you’re on an IFR flight plan.

In fact, I think it’s a good idea to get in the habit of filing IFR from time to time on all except local flights because it helps keep procedures sharp and maintains a pilot’s awareness of how the “system” works.

The second rule, under FAR 91.413, is the transponder rule. 91.413, “ATC transponder tests and inspections,” states: “No persons may use an ATC transponder that is specified in 91.215(a), 121.345(c), or Sec. 135.143(c) of this chapter unless, within the preceding 24 calendar months, the ATC transponder has been tested and inspected and found to comply with appendix F of part 43 of this chapter.”

While the transponder test is required for all aircraft, there’s quite a bit of national airspace where a transponder is not required. This airspace is spelled out in FAR 91.215, but realistically, keeping your transponder check up-to-date assures that your system (and the airplane) is legal to fly almost anywhere in the country. Easier to just “get ‘er done.”

Many maintenance shops can perform both 91.411 and 91.413 tests, provided they have FAA approval in the form of a repair station license for these tests.

Avionics shops, manufacturers of the airplane, as well as a few other places also have this equipment.

Some folks grouse a little bit about the costs—which range from $200 to $300 for both certifications—but it is important to realize that the equipment needed for certifying your system also should be recertified on a regular basis, and that costs the shop some bucks, too.

I hope that answers your questions.


Happy flying.

 

Q: Hi Steve,

My mechanic wants to remove the horizontal tail feathers off my old Apache for what he says is an inspection from corrosion of the tube.

What’s he talking about?


—Apache Al


A: Hi Al,

Your mechanic is talking about Piper Service Bulletin No. 1160. It was issued in 2005 and calls for an inspection of the stabilator torque tube for internal and external corrosion.

The torque tube is a steel tube that ro-tates on large roller bearings that are supported in two-piece housings securely bolted to the aftmost bulkhead in the fuselage.

Since the left and right stabilator “tail feathers” are not normally removed during yearly maintenance, and since corroded torque tubes have been found, I feel that this is an important inspection.

I had to remove the tail feathers on my Comanche to comply with AD 2012-17-06 that related to an inspection for cracks in the stabilator horn. I did the inspection called for in SB 1160 at that time. AD 2012-17-06 does not apply to your Aztec.

Since my Comanche had spent much of its life near Phoenix where corrosion and rust rarely occur, I didn’t have any problem pulling my “feathers.”

However, I did do my best to soak the tube with AeroKroil before and during removal. The key to removing my feathers was to go slow and continue to apply Kroil.

I twisted the feathers slightly at first, and then more and more on the tube, and eventually they slid off.

SB1160 provides both a minimum outside diameter for the torque tube (2.3113 inches) and a minimum tube wall thickness (0.161 inches).

If there’s any deviation due to rust, the tube must be replaced. The part number for the tube for your Aztec is 16067-00. I just checked with Piper and was told that part number 16067-00 is no longer available.

If your torque tube is airworthy, make sure to apply a protective coating after the inspection. If it isn’t, a used serviceable torque tube assembly may be available through a salvage yard.

According to Tom Pentecost at DSA Flightline Group, owner of Piper Parts Plus (P3), the replacement kit (p/n 652-579) listed in Table 1 on page three of the service bulletin is still available with a lead time of 100 days.

 

Steve Ells has been an A&P/IA for 44 years and is a commercial pilot with instrument and multi-engine ratings. Ells also loves utility and bush-style airplanes and operations. He’s a former tech rep and editor for Cessna Pilots Association and served as associate editor for AOPA Pilot until 2008. Ells is the owner of Ells Aviation (EllsAviation.com) and the proud owner of a 1960 Piper Comanche. He lives in Templeton, Calif. with his wife Audrey. Send questions and comments to

RESOURCES >>>>>

Penetrating oil
Kroil/AeroKroil

 

Piper replacement kit 652-579
Piper Parts Plus (P3) – PFA supporter

 

Further reading
FAR 91.411 and FAR 91.413

 

Piper Service Bulletin No. 1160
PiperFlyer.org/forum under “Magazine Extras”

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