Bolt Torque Check at Annual

[jiott]

I have a question about checking bolt torque at annual. I used the red Torque Seal brittle lacquer on all my bolts after torquing them to spec during my build. When it is time for annual condition inspection, the checklist says to check bolt security/torque. Is it sufficient to just look at the red seal to verify that the seal isn't broken and the bolt hasn't moved, or must I actually put a torque wrench on it and check the torque? What do you AP/IA guys say?

Jim

[jiott]

I am tickling this thread, hoping to get some replies from some AP/IA out there.

Jim

[PapuaPilot]

That is a great question Jim and you may get a range of answers.

I am a aircraft maintenance instructor, A&P for 30 yrs. and working on my IA.
Here is what we teach where I work.

-If the torque putty has not been disturbed and isn't cracked then you don't need to recheck the torque. BUT you need to be 100% sure that the lacquer didn't get put on over some oily threads; I have loosened nuts only to see the torque seal turn as one piece and can appear to be undisturbed. The trick is to make sure the bolt/nut is TOTALLY clean and dry before you put on the lacquer.

-If there is any doubt about the torque then retorque the fitting.

-If the torque seal is all or partly missing then check the torque and remark the fitting.

FYI I have seen several articles about checking torque and most agree that it is not enough to just put on a torque wrench and "see if it turns" (which many do and I did for many years). The only way to truly check the torque would be to loosen the fitting and torque it again. A good example of a would be an exhaust riser nut; you could check the torque and not have the nut turn because the nut is corroded to the stud and still be loose. In this case you would need to break loose the nut and torque it again.

Other pointers:
-Remember that as you torque various fittings you need to take into account and drag/friction torque if there is any (i.e. the torque needed to just make the nut turn) and whether it should be a wet or dry torque (rule of thumb: generally all airframe torques are dry and all engine torques are wet). If you forget to add friction torque and/or do a wet torque then the fitting will be under torqued.
-Certain bolts should be left alone such as the through bolts on an engine unless you are 100% sure that it has spun.
-Always use a torque wrench, but has your torque wrench calibrated?
-I usually check/redo the torques throughout an engine several times after a new installation. Usually the exhaust, intake and anything with a gasket will be a little loose due to the gaskets settling in. I also want to make sure that the manufacture or installing mechanic didn't overlook or mistorque something during assembly and installation.

I hope this is helpful.

[jiott]

That is great information! Just what I was looking for.

JIM

[jiott]

Here's another question regarding annuals:
I am planning to do my "annuals" on a 1 year calender basis. The Rotax maintenance schedule calls for the inspections on 100 hour intervals. I think I will be flying roughly 100 hours per year, but it will vary of course. How do you guys mesh this together? Do the "annual" for everything except the engine, and do the engine part at 100 hour intervals? This is probably a dumb question, but hey, I am new to this.

Jim

[Dave S]

Hi Jim,

I don't think it as dumb question at all.....the situation can seem more than a little ambiguous what with the fuzzy mix of regulations, engine manufacturer recomendations, and experimental aircraft.

This is one of those things I am pretty sure people do in it various ways and they can all be "right"....

The requirement for an annual condition inspection is pretty plain as a regulatory requirement; however, many maintenance points will not coincide with the annual schedule....some may come earlier and some may come later. The Rotax 100 hour, at least in the context of experimental aviation could arguable be considered not to be a regulatory requirement. But if we didn't do it and something broke, and the issue was memorialized in the NTSB files, there might be all kinds of pointed questions directed at us. I'm going with the 100 hour guidance recommendation.

......consider an ELT if one is required to be on board. Your annual condition inspection includes a check to see if it is there and if it works; but, the battery may have a 7 year scheduled replacement...the $135 battery is not going to be replaced at annual condition inspection.....at least not by me.

The Rotax scheduled maintenance can be treated the same way; particularily if we take part of the page from the book for certain non-experimental boys titled "progressive maintenance" ...replace or accomplish scheduled things when they are due...irrespective of if they coincide with annual time.... this can certainly be a resource ($) preservation tact.

At annual condition time, I check and verify everything that needs to be; however, items like the rotax 100 hour get acomplished when 100 hours is up unless there is some other reason inspiring attention before 100 hours.

I find that the aircraft log book has enough pages that I am not concerned about using them up with addittional entries between the annual condition entries

As the aircraft manufacturer, you have the option and responsibility to determine scheduled inspection/replacement/repair intervals based on logically solid documentation with the exception of items defined by regulation (like the annual condition inspection).

Sincerely,

Dave S

[PapuaPilot]

Hi Jim,

Dave gave some great answers and examples.

My perspective comes from inspections on certified aircraft. After I complete my KF I will deal with the conditional inspection issue. I equate the conditional to the annual inspection for certified aircraft. The 100 hour inspection is only required for planes used for hire/commercial purposes. This means a privately flown plane could fly 400 hours in a year with only an annual (legal but not very wise).

Here is how I would approach the Rotax 100 inspection in regards to the annual conditional inspections.
-If I flew 100 hours or less a year I would do the entire Rotax 100 hour checklist at the annual. I'm not familiar with Rotax but assume that you are looking over the engine systems and doing some servicing (oil, filters, plugs, etc.). Even if I only flew 10 hours I would want to go over then entire list.
-I you fly more than 100 hours a year than you would want to do the 100 hour stuff every 100 hours and also (again) at the annual.

Progressive inspections are for planes that fly lots of hours, usually far more than 100 hrs/yr. Part of the thinking is that because the plane is getting used a lot certain things don't need to be looked at every 100 hours/annually. Other things will get done every 50 or 100 hours.

Lastly, there are probably going to be things to inspect on the Rotax engine that fall at intervals higher then 100 hours or annually. In that case you should track these at do them at or before the required time/date. An example would be the gearbox inspection.

Phil

[jiott]

Thanks Dave and Phil. Your replies make a lot of common sense and really help me in my maintenance planning.

Jim