Wheel pant bolts coming out regularly

[Bill3558]

Whats it doing to my cruise airspeed without pants?

[sandpiper]

I had my wheel pants off years ago for a short time. I think the penalty was 3 knots. To me, the plane looks better with them on.

[Tom Baker]

16 hours ago, Roger Lee said:

Here's another example. If an aircraft company like FD has a part number assigned to a part you MUST buy it from them and that's straight from the FAA. Who has ever bought a part not directly from FD? Ooch  (Tom have you purchased items not from FD  ) We all have. There has even been times when FD told people including myself to just buy it somewhere else with nothing in writing.

That is not exactly true, it depends on the part and the description in the part manual. Any place that the description provides a specification or a specific part number you can use that part. Examples of that are almost all the hardware and hoses. A quick glance at the parts and assembly manual found others, like the upper rudder bearing, and the cooling fans in the instrument console. This is no different than standard category aircraft.

[Roger Lee]

"That is not exactly true, it depends on the part and the description in the part manual. Any place that the description provides a specification or a specific part number you can use that part."

Not according to the FAA. If that part was assigned their own part number from the aircraft MFG then you must buy from the aircraft company. The FAA was very specific and gave an example and here it is. Some aircraft use a Timpken wheel bearing. The aircraft Mfg has a part number assigned which you buy from them. You can buy the bearing from Timpken, but the FAA says aircraft Mfg's may put parts through a testing procedure to make sure they are good and won't fail. You may not even know this about the individual part. This is why you must buy from the aircraft Mfg if it has an aircraft part number assigned from the aircraft Mfg. So the FAA was very specific when they gave that example that any part from the aircraft Mfg that had an assigned part number had to be purchased from them. Now go back through the FD parts manual and look at all the part numbers for minor items like screws and tons of other items. FD has actually violated the FAA mandate too, but most things are so minor no one takes issue.

Now the reality check. Just like the one you guys were very specific on with Loctite on the wheel pant screw and following the manual "TO THE T". People do go out and buy the Timpken bearing from someone else because it may be cheaper. How would anyone know. Well some aircraft Mfg's stamp a number on the part when they get it. Other than that if the FAA really wanted to be super nosy and nit picky when investigating you they could call the company that keeps records of their sales to see if you ever purchased that part from them.

Bottom line we are all guilty of some infraction if you want to take it to the enth degree. i.e. No Loctite on the wheel pant screw or parts purchased from someone else that has an FD part number in the manual. Does anyone really go over the top to care? Depends on the magnitude of the infraction I guess. 

So the SUBJECTIVE argument would be how far does each individual want to take it. Happens all the time even on certified aircraft.

[Tom Baker]

1 hour ago, Roger Lee said:

Not according to the FAA. If that part was assigned their own part number from the aircraft MFG then you must buy from the aircraft company. The FAA was very specific and gave an example and here it is. Some aircraft use a Timpken wheel bearing. The aircraft Mfg has a part number assigned which you buy from them. You can buy the bearing from Timpken, but the FAA says aircraft Mfg's may put parts through a testing procedure to make sure they are good and won't fail. You may not even know this about the individual part. This is why you must buy from the aircraft Mfg if it has an aircraft part number assigned from the aircraft Mfg. So the FAA was very specific when they gave that example that any part from the aircraft Mfg that had an assigned part number had to be purchased from them. Now go back through the FD parts manual and look at all the part numbers for minor items like screws and tons of other items. FD has actually violated the FAA mandate too, but most things are so minor no one takes issue.

As an aircraft mechanic with inspection authorization I do 8 hours of continuing education every year at an FAA hosted meeting. This very subject has come up and been answered by the FAA in the meeting. For example Cessna has a wheel bearing part number 12345, and the description is "wheel Bearing". You have to buy Cessna part 12345. Piper has the same wheel bearing part number 56789, and the description is "Timken number XYZ". You can buy either Piper 56789 or Timken XYZ. Now both aircraft use Cleveland wheels and both use the same Timken bearing. It all depends on the detail in the parts description. Hardware is the same. If they list for example AN4-22A you can buy that part anywhere. 

[Roger Lee]

There is nothing better than a good educational debate. You gotta love it.  

 

" For example Cessna has a wheel bearing part number 12345, and the description is "wheel Bearing". You have to buy Cessna part 12345. Piper has the same wheel bearing part number 56789, and the description is "Timken number XYZ". You can buy either Piper 56789 or Timken XYZ. Now both aircraft use Cleveland wheels and both use the same Timken bearing. It all depends on the detail in the parts description. "

So how would you know if one company did different testing and had different specs for their particular use? That's why the FAA told me you have to buy from the appropriate MFG. What happens  if the aircraft MFG changes the part in some way. You'd never know, but has the same part number.

So here is another example of the right hand doesn't know what the left is doing at the FAA. I talked to them about every two weeks years ago in Oklahoma. I was doing lots of research projects back then. I found few FSDO's that really knew any correct info about LSA and some didn't know the FAR's as well as they thought. There were a few in Oklahoma that actually knew what they were talking about and knew exactly where to go in the FAR's to show a documented reg. Then even some of these over the years were challenged and sent to the FAA legal and that's where some of our interpretations came from since 2003.

That instructor may have said that of which I have no doubt, but I have found many FSDO's  and instructor's wrong. (and they are never happy when you prove it to them) I always call the top guys in the FAA that work with the regs. That way I don't get 3 different answers. I have proven a half  dozen FAA guys wrong and then they ask me why did I ask if I knew the answer. I tell them because I wanted to know if they were all on the same page. They aren't. That makes some unhappy, but then they know. When it comes to LSA stuff I find quite a few FSDO's and even people in Oklahoma really don't know, but will tell you anyway then I refer them to the correct page in the FAR's. We can't always rely on correct info coming from the individuals in the FAA or outside instructors.

So here we are. Your instructor says it's okay and the guys at the FAA in Oklahoma say it's not. So who do we believe and how do we get the right info? I always take them to task and research then I call them back with what I found. I've done that with LSA MFG's too. Sometimes they change things and sometimes they don't.

p.s.

I've misspoke as an instructor before too. Over my lifetime I've had to correct myself as a Homeland Security instructor, ACLS, para-medicine, firefighting and a Rotax instructor before. Better to get it right than keep spreading misinformation. I believe we're better for it if we just acknowledge it, correct it and move on with the right info for the next guy or class.

p.s.s.

Tom why not research what the instructor told you and if you find out different call him and if not you'll be 100% sure. It's a win for everyone.

[John Vance]

I was a project engineer for Bendix/Allied Signal/Honeywell for many years and have seen the part number issue from point of view.  At the location where I worked,  one side of the business made made fuel controls for turbine aircraft engines, and the other made aircraft landing gear components, including wheels and brakes. Both sides were working both commercial and military projects. We manufactured some parts, so “change control” of those parts was done internally and was fairly straightforward, because we knew exactly how those parts were to be used. Many components were outside of our expertise, though, and bearings were a perfect example. Others included such things as electro-hydraulic servo valves, solenoids, transducers, etc. For those items, we created “source control drawings”, with a Bendix (or whatever) part number, which included some critical fit/form/function details, the specific supplier, and their part number.  Changes to parts are routinely made, by every supplier, for many and various reasons. Most changes are trivial and affect only the part’s revision letter, not the part number. But this can be a fine line. Suppliers don’t necessarily understand the impact of a seemingly trivial change to a part that may have many end uses. Therefore, for these “source control” parts, suppliers are required to submit descriptions of minor changes for review, to ensure that these changes are OK.  Mil-spec parts are fine for some things, but sometimes you need to dig deep in the spec to make sure. For us as end users, this stuff can seem ridiculous, and from the project engineering standpoint it can make your head want to explode. But it basically boils down to change control. Hope this clarifies things a little.

[AGLyme]

Great posts John and Roger
At the end of the day fellas it all boils down to a human being‘s interpretation.