I just ordered two new intereference fit bolts for mounting an (admittedly) important part of my aircraft. It’s the mount of the stabilator.
These two interference fit bolts are about 10 centimeters long and look more or less like any ordinary screw. Now I do not mean to complain, it’s just like another “Alice in Wonderland”-moment, and I always like to unterstand the circumstances to put things into the right frame. Can anybody tell me why one of these intereference fit bolts is sold at 150 Dollars? (needless to say that it’s only available in the U.S.) Does this represent only the “market price”, (because it’s mandatory to regularly check and typically replace these bolts, and it is a point where you can grab into the wallet) or is anything technical behind which somehow justifies the costs?
I wouldn’t have wondered over 20 or 40 Dollars, but this? It’s 300 Dollars for two bolts…
Depends on how precise the interference fit is intended to be.
If it’s very precise indeed then the bolts might be manufactured to an incredibly tight tolerance. That would also explain why they need to be replaced regularly, as they easily wear out of tolerance.
I’d say a captive-market wallet raid is more likely, perhaps with a bit of the above thrown in and also low production volume.
It’s all about the market…once you have your fabrication set up, the cost of manufacturing is very low.
It’s the setup cost over ‘x’ number with ‘x’ being appallingly low.
A lot of those are however old production runs and thus mostly market-driven. Who wants to hold on to $10k worth of 500 ea single-application bolts only to sell a dozen a year , and then charge only $30 each?
$4 for the bolts, $296 for the paperwork and profit
Some bolts for Airbus helicopters (AS350) cost 1.5k. 0.15k is rather cheap if you ask me 
On my Onex there are several bolt connections that are reamed to precise fit in the wing fold mechanism using an adjustable reamer. If that gets sloppy, the only alternative is to re-ream with a slightly larger bolt/pin. Today ordinary AN bolts are used on a few of them, but these are market and will only fit at that position because of the lack of tolerance in AN bolts.
But changing a high tolerance bolt without doing anything to the mating hole? why? What is wrong with the original bolt? corrosion?
Who are you buying the bolts from? Are they standard bolts? What does the parts manual for the aircraft call for?
If you have the part number, Aircraft Spruce might be able to sort you out. A search for “close tolerance bolt” yields a number of results at moderate prices (up to $15).
Places like McMaster will also sell you something like this for $5 to $25 a pop (standard or precision fits, to various tolerances, material certs available for some), but it is not clear if this will satisfy the aircraft manual.
https://www.mcmaster.com/bolts/shoulder-screws/steel-hex-head-shoulder-screws/
But if you need something custom from Mr Piper (or others), it is going to cost you :-).
@Canuck I looked up other prices in the web and the lowest I found was close to 150 Dollars – same price as in the store where I’m just becoming a good customer. They come certified, of course.
@LeSving it’s not a big bolt to mount the wing or something similar, it’s more a locking screw. About 7mm in diameter. The bolts have to be removed in order to perform a check for cracks (it’s an AD), however it has never been complied with on my airplane since new. So I am not so concerned about the decision to put new bolts there, but another interference fit bolt on my tail which also needed replacement comes for about 2 Euros. Just was puzzling about the spectacular pricing.
UdoR wrote:
The bolts have to be removed in order to perform a check for cracks (it’s an AD)
Is it to check for cracks in the bolts themselves, or that you must remove them to access something else that you’re checking? If the former, were they cracked?
Or are you just replacing them because new ones might be nice?
It’s the famous (at least amongst Comanche owners) stabilator horn which had to be checked. Check was ok.
The bolts in question affix that horn to the stabilator torque tube. They don’t have to be checked.
Next time I’m gonna replace it with the famous (amongst Comanche owners) “Aussie horn”, but that’s another story. This time I just want to be back in the air ASAP….
