47U

This looks like a better explanation, thanks. My interpretation is that you can depending on what you consider a change in weight? Does it have to be appreciable? Consensus on how changes in weight constitute a major alteration have evolved. Major alterations change the maximum gross weight, and/or forward/aft C.G. limits. Have your A&P recalculate the new empty weight and C.G. arm change as a minor alteration. In all likelihood, since you’re only talking about ounces vs. pounds, he’ll sign it off as ‘negligible’ change to w&b. Yup, talk to your A&P first. And/or your IA, if they’re different people. tom

https://www.faa.gov/documentLibrary/media/Advisory_Circular/AC_120-77.pdf There’s a logic tree on the last page of this AC. As long as you use approved methods and materials (your A&P might determine the dome light meets approval after inspecting its design and construction). Otherwise, use mil-spec wire, switch, and circuit protection and you should be able to get it signed off as a minor modification. If you can convince your A&P. tom

That’s the kicker. If he’s two months late doing ‘scheduled mx’ that’s not a schedule. If you thought you’d patched up previous ‘sideways’ situations, then remind him that you didn’t approve this mx. Then offer to prorate the charges for the amount of time now extended in the IFR cert. $400 every 24 months works out to about $16.67/month. If it’s four more months you get, offer him $100 and you’ll contact him if 24 months for the recert. He gets something for his time and opportunity for future business vs. the option to file the receipt where it will not be subject to fading by the sun. tom

Nice research, Bob! You proved the dual keyway gear rumor to be true. Ironic that you found the reference PN at Aircraft Magneto Service who overhauled my right mag (basically sent me a new one for about .8 amu). The old one was the wrong part number (???). The new mag runs perfectly. Not wanting to change out both mags on the same annual (if it’s not broke, don’t fix it), I swapped the left mag to the SureFly the following annual and include as benefits no more 500 inspections and getting rid of the shower of sparks. If it’s not installed, I don’t have to maintain it. So far, so good. tom

Let’s hope servicing of your pump solves this issue... we’re all curious as to what the shop discovered inside the pump. tom

When did you first discover the flaps were not working on the ground and what mx was performed immediately prior to that discovery (if any)? tom

My Bendix gear had a single keyway, but my understanding is that there’s an alternate pn magneto drive gear with the keyway indexed 180 degrees out, i.e., the keyway is in between two of the gear’s teeth, as opposed to aligned with a gear tooth. How far are you out? The closest I got was 1.5 degrees after TDC, and it runs great. I talked to SureFly about it and they said it would be fine. Eventually, I’ll scrounge up the proper gear so I can get the timing dialed in to 0 degrees TDC. tom

Thanks for your info, @Cody Stallings. Sounds like the tolerances are pretty tight, if etching can have an affect. Hopefully the teflon inserts are leak free, being there’s oil in the hub now. How about blades? Absent any major nicks, how many overhauls can I expect before I need one or more blades replaced? I do like getting a prop back that looks brand new, but I’m guessing there’s a cost to that, eventually. tom

Cody... thanks for your expertise, though I think you’re mixing info between the OP and my post. OP has 950 hrs his prop, new in 1988, and was throwing a little grease, mine is 30 yrs old on its 3rd overhaul and needs the teflon inserts. It’s a little over 1400 hrs TTSN and 600 SMOH. So, why is my hub worn after 1400 TTSN? Corrosion? There’s no external evidence of that, although it was in Northern Iowa (hangared on a farm strip) from new in 1990 until 2008 when I brought it out to NORCAL. I’m hangared, albeit in a somewhat leaky T-hangar that the rain blows in some (Oct-Apr) through the fold up door. Is the teflon insert mod good for another 10 years? If I’m not experiencing any problems, should I extend the overhaul interval? I was concerned last annual about the one blade with a little more wiggle than the other two... and it’d been10 years. It’s that paranoia thing I got going for me. Again, thanks for your expertise. tom

Well, my 30 year old McCauley will make it through the overhaul, but it needs teflon inserts in the hub because the blade o-ring seats are worn, about a 1 amu hit. An option, I’m told, that wasn’t available up to just a couple years ago. Sooooooo, I’m up to 4.9 amu. Better than 10+(?) amu for a new prop, or a coupIe amu for a new hub. I’m lucky I have an understanding comptroller... Last annual, the prop had some fore/aft play in one blade in particular, but it was within spec and didn’t show any evidence of throwing grease, ever. I wonder if I’d delayed the overhaul and run it another year or three, if it would have worn enough that the teflon insert fix wouldn’t have been an option requiring a new hub. When the teflon wears, that can be replaced. I’ll have to ask how many hours they figure the teflon lasts. Scheduled mx is sometimes expensive. Deferring scheduled mx is sometimes more expensive. The prop is under tremendous stresses. For me, having confidence in the prop is worth the piece of mind. Besides, I just purple-polished the spinner.

The hi/low vacuum lights were on the original attitude indicator, which was replace long ago. When I got the airplane, I added a low vacuum warning light, then during some panel work a UMA vacuum gauge, and have since replaced the AI with one that has a flag. And I time-changed my vacuum pump last annual. Am I paranoid? tom

I’ve got the 3-blade McCauley on my C. I think McCauley recommends a 5 year overhaul. It was first installed in 1990, then overhauled in 2000, I got the airplane in 2008 and overhauled it again in 2010. It was about 2.5 amu. Now it’s 2020, another 10 years went by pretty fast. Ameritech in Redding overhauled it in 2010, and they just picked it up last Friday, said it’d be back in 2 weeks. And about 3.4 amu. He also said they’re now putting oil in the hub, not grease. They made that change a couple years ago. tom

X Plane can be an excellent tool for practicing procedures, learning to stay ahead of the airplane. But, I agree with MikeOH. Bad habits can be hard to undo. And the X Plane panel might not be anywhere near to what you’ll end up flying. Go get your PPL written done first and get some lessons under your belt with a CFII. Tell him what your aspirations are and follow his lead. You might be further ahead in the game if you don’t take too big a leap in the beginning. tom

I guess it might depend on how tired your vacuum pump is, and how well your vacuum regulator adjusts. I just put a new pump on last annual and commonly see 1/4” loss of vacuum at 5000’. Maybe my regulator is more tired than most? Another reason to go glass and ditch the nostalgia. tom

Ok, I’ll join in... Especially for 9K... I do like the look of a vintage panel... glass is great, but there’s no nostalgia. Guess I’m a dinosaur. tom