Panel Upgrade Progress/Mission creep

Well I've been putting in some serious hours trying to get the -8 to an IFR status while performing the condition inspection and thought I'd share some of the progress and dilemmas I've been incurring. To preface, I did not build the airplane so I am 'righting' some previous owners/builders handiwork to my preference/specification. Right now the biggest threat to the timeline is mission creep; it seems like the further into the airplane I dig the more I find that needs/I want to have corrected. I think the crux will be sorting out the needs vs the wants. I'd like the opinions of those out there in sorting out some of these needs vs wants. Here's some photo updates:

As she sits:



The panel minus the electric artifical horizon not mounted:



The aunnunciator strip a la Paul Dye (shamelessly copied)



What kind of alt mount am I looking for? Case or Boss mount? I purchased a Boss mount kit from vans and it doesn't look like the puzzle pieces fit together for a 12 and 6' oclock mounting auto alternator (yes, I'm decided on the auto alternator)



This clearly needs to be fixed, each prop bolt is approx 3/4'' too long so a total of 5 washers are added to correct the length. I can a) buy new bolts for $200 or b) cut the length and file/run a die over the threads. And yes it surprised me to see no safety wire, they will be safety wired after replacement/cutting.




Finally, I'm relocating the old fuel gauges from the panel to just next to the fuel selector valve. Can I get rid of both of them and just use a fuel totalizer from EI? We all know the resistance floats are worthless but I'm unfamilar with the CFR that might require me to retain them. As always, thanks for the input. Looking for info on the alternator mount ASAP. I will give consideration to all suggestions and act on the prudent ones.

Also!

I forgot to ask about the best way to drill out the remaining 40 or so rivets holding in the L & R 'half moons' that the panel mounts too. Not looking forward to that one.

RVZoomie said:

To preface, I did not build the airplane so I am 'righting' some previous owners/builders handiwork to my preference/specification. Right now the biggest threat to the timeline is mission creep; it seems like the further into the airplane I dig the more I find that needs/I want to have corrected.

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Welcome to the club, I'm now 3 months into a 2 month panel upgrade with no end in site. In addition to an all new panel I'll have: New electrical system, new antenna wiring, all new FWF plumbing, new alternator, new firewall insulation....

Mark,

Regarding the prop bolts: there are those who will tell you not to run a die over them because AN bolts have rolled threads, not cut threads. True enough but when I encountered the $200 prop bolt dilemma on my Long-EZ I bought grade-8 bolts at an industrial fastener place and had a friend drill holes for safety wire on his mill.

Regarding the alternator: I've gone full circle on my RV (under construction). I looked at older N-D automotive alternators like Van's used back in the day but they have a checkered reliability history and I didn't like what is available nowadays (Chinese clones, poor rebuilds). I installed a newly rebuilt Delco CS-130 alternator but it's heavy and interferes with the cowl, especially the 4-inch pulley that I managed to come up with. So I yanked it out and installed a B&C L-40 externally regulated alternator for $400. Wish I had done that in the first place and wish I had used B&C's mounting hardware instead of modifying Van's to fit, buying and drilling my own bolts, and buying a belt.

I get over to Spokane occasionally (used to live in Coeur d'Alene); maybe I could met up with you at SFF some time.

--
Joe

Boss mount is the mounts you have...hence the mounting boss on the engine case. "Case Mount" refers to the need to install a distinct and separate bracket onto the case via the case half bolts to then mount the alternator to.

Regarding the prop, just go buy the right bolts (to be blunt and no offense intended, I'm already not a huge fan of what you've got there at the moment).....this isn't a garage built soapbox racer; it's a +/-$100K airplane we're talking about here! To that end, just go buy a good alternator as well (PlanePower, B&C, etc..).

Also, whilst the fuel totalizers are super accurate on the entire fuel burn, unless you keep a very accurate "time on each tank" notepad you'll not have a good way to know levels in each tank; so I'd say keep the guages unless you put them into the EIS or something (to that end, you know you can add fuel flow to the EIS as well without having to buy another box).

Just my 2 cents as usual.

Cheers,
Stein

FAR 91.205 says you need a fuel gauge "for each tank", so I don't think one totalizer can fulfill this requirement. I'm assuming your operating limitations require you to observe 91.205 for ifr operations.

Thanks for all the replies. Stein, the washers and incorrect bolts are obnoxious. It's amazing the disparity in workmanship between certified mechanics. I inherited those from the builder. I'd really like to use a fuel totalizer which I feel would give a much more accurate picture of my fuel status but will adhere to the FARs. Several business jets I flew used information from the totalizer alone. Back to the hangar to do work, I'm sure more questions will arise. Thanks again!

Panel update

Got the panel covered with the CF vinyl and the annunciator strip mounted.

RVZoomie said:

This clearly needs to be fixed, each prop bolt is approx 3/4'' too long so a total of 5 washers are added to correct the length. I can a) buy new bolts for $200 or b) cut the length and file/run a die over the threads. And yes it surprised me to see no safety wire, they will be safety wired after replacement/cutting.

Click to expand...

Regardless of the cost, buy the correct bolts, don't try to modify (ruin) the bolts you have. Prop bolts are one of the most safety critical items on your plane.

Finally, I'm relocating the old fuel gauges from the panel to just next to the fuel selector valve. Can I get rid of both of them and just use a fuel totalizer from EI? We all know the resistance floats are worthless but I'm unfamilar with the CFR that might require me to retain them.

Click to expand...

The standard float senders work great with EI gauges. I've been flying floats with an EI dual fuel gauge since 1999, it is accurate within a gallon or so.

Thanks for the advice,

As with all aviation suggestions and advice, I like to see the source reference matieral. Please don't take offense, I accept most information with similiar scrutiny. I certainly have no issues in spending money on quality components or safety critical components. That being said, someone with similiar 'certified credentials' left the bolts in there by accident or on purpose and they have so far (key term) worked for several hundred hours (~500). I was not aware that cutting bolt length would change any tensile strength properties, is there technical/engineering evidence that would suggest otherwise? Any historical evidence of being a common failure point? If I cut, I won't be using a die to clean the threads near the cut, most likely a thread file. As for the resistance floats, I have had multiple issues with the floats sticking and have learned not to trust them at all as has been my experience with some certified aircraft. Burning on time, or starting with a known quantity and subtracting usage has always worked best for me. I understand that some of my thinking may be unorthodox or not the official solution but this is one of the reasons why I enjoy experimental aviation so much.

As Sam suggests, the resistive senders are amazingly accurate. Yes, they can and do have issues, I had to replace one side in my 500 hours. But, what they do give you is another data point added to the totalizer and your good head, clock, and math. I had my fuel flow sender go bad very gradually. I knew something was wrong when the math between it, my resistive guages, and my brain didn't add up.
I am a fuel chicken, so having three things I can compare to make sure I know what I have on board when things get low is important to me.

Call your local prop shop and talk to them about the bolts.

Good luck on your rebuild and I have no doubt it will be a far better airplane when your done.

gtmule said:

Welcome to the club, I'm now 3 months into a 2 month panel upgrade with no end in site. In addition to an all new panel I'll have: New electrical system, new antenna wiring, all new FWF plumbing, new alternator, new firewall insulation....

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Ha! Me too. Now 3 months and 2 weeks in. Getting short of time before may formation clinic!

Solution

Found a good compromise between purchasing new bolts and attempting to modify the prop bolts. I had a machinist make spacers the same dimensions as the stacked washers and will be installing them soon when I add the new alternator pulley. To date I have added, repaired or replaced:

Electrical system
Alternator
1 comm ant
1 nav ant
1 xponder ant
heated pitot
remote compass
painted interior
'golf tube'
elec aileron & elev trim
infinity stick
instrument panel
pitot/static system
gps shelf
air/oil seperator
prop bolts
remote O2 system
probably more... I'm exhausted.

RVZoomie said:

Found a good compromise between purchasing new bolts and attempting to modify the prop bolts. I had a machinist make spacers the same dimensions as the stacked washers and will be installing them soon when I add the new alternator pulley. ....I'm exhausted.

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Really?!? Please take this the right way, but I would STRONGLY encourage you to just go buy the right and correct bolts and quit fooling around with expending all the energy, time, and money to simply put a band-aid on something that is clearly incorrect to begin with. Again, I'll remind you that you're dealing with a $100K airplane here, and the correct hardware simply isn't that expensive.

Just because the last person put stacked up washers on there (and yes I've seen it done before...but it still doesn't make it a good practice) doesn't mean you should or can continue the kludge by making a nicer band-aid. Are you going to clearly tell folks that you give a ride in that airplane that you have the incorrect bolts coupled with some "custom" machined spacers (out of who knows what metal) that hasn't been engineered, tested or approved before you take them for a ride?

Again, no flames intended...but we're not talking about something cosmetic here...it's a prop on an airplane!!!! Believe me, props CAN and WILL kill or severely inujure you if you don't treat them right. I know this sounds a bit harsh, but it's absolutely incredible to me that someone would knowingly continue to do something incorrectly when folks have pointed out that error and relative to the value of the airplane it's peanuts. Just because it's worked for ~500 doesn't mean it won't come apart in the next 500 minutes. I'm just surprised you'd dink around with this over a $300 set of bolts that you can order online: http://www.sensenich.com/products/browse/9.

My 2 cents as usual. It's your plane and you can do with it as you wish, but things like this are what give homebuilt airplanes and their owners/maintainers some of the negative reputations you sometimes read and hear about. On this one I guess we'll just have to respectfully agree to disagree. Perhaps I'm the only one who finds this a bit incredulous....but with all the discussion on safety over the past month, I'm just voicing one guy's opinion, so take it for what it's worth!

Cheers,
Stein

And when all else fails the words from the "Bible" apply (AC43-13):

7-37. GRIP LENGTH. In general, bolt grip
lengths of a fastener is the thickness of the
material the fastener is designed to hold when
two or more parts are being assembled. Bolts
of slightly greater grip length may be used,
provided washers are placed under the nut or
bolthead. The maximum combined height of
washers that should be used is 1/8 inch. This
limits the use of washers necessary to compensate
for grip, up to the next standard grip size.

Drawing C4 shows those washers as AN970s, not AN960s, and only one.

Buy the right stuff and do the job correctly. As my mentor told me when I started building: "There's no half-@ssed s**t in airplanes."

Just my .02.

Yep.

I'm in the same corner as Stein and others.

I can see the NTSB report now..."Unapproved prop bolt spacers were used......"

Please get the correct ones.

Best,

Purchasing new prop bolts

After turning some spacers on the lathe I've decided to purchase new bolts. I can post some pictures of where the previous bolts actually cut into the cheap washers used. From the looks of it, I imagine the bolts were over torqued as well and the bolts most likely had some stretch in them. Hope I didn't upset too many people, I just wanted a technical reason to as why the spacers wouldn't be a valid solution.

C-130 wings are held on with bolts using about an inch of spacer, and the bolts on the horizontal stab have quarter inch spacers and/or a weird spacer/bushing combinations.

On a bolt as long as our prop bolts, an extra washer won't make a difference in clamp load or strength PROVIDED that it's sufficiently hard. That said, you did the right thing, since those bolts had possibly been over-torqued.

RVZoomie said:

After turning some spacers on the lathe I've decided to purchase new bolts. I can post some pictures of where the previous bolts actually cut into the cheap washers used. From the looks of it, I imagine the bolts were over torqued as well and the bolts most likely had some stretch in them. Hope I didn't upset too many people, I just wanted a technical reason to as why the spacers wouldn't be a valid solution.

Click to expand...

I don't think you upset anyone (at least I wasn't upset)...we're just trying really hard to push you to do the right thing; which you obviously decided to do - GOOD FOR YOU! There have just been way to many instances of kludges that didn't work. As others have noted, spacers/washers are obviously fine when a part is engineered for it. In this case that prop wasn't engineered to have 3/4" spacers under the bolt heads.

I'm happy to see you taking the time to rectify the 'issues' that you inherited. You already have a nice plane, but it'll be even nicer (and safer) when you're done. That said, if the original builder is reading this thread...he should know he made a very poor and unwise choice.

Cheers,
Stein

The other thing is...NOTHING wrong with cutting bolts, the cut up part should be past the bit that sees any stress. Some sort of corrosion control on the cut face is nice (goober out up with anti-sieze). Don't use a die, just use a needle file on the last thread or so...

Usually won't work on AN or similar bolts though...the threads are already so short... And don't even THINK ABOUT adding threads with a die or lathe...death will ensue...

To the poster above who used GR-8 bolts, that's generally a bad idea. AN bolts are actually closer to GR-5. GR-8 can be quite brittle and may eventually fail in fatigue loading (though they do have a higher ultimate strength Than GR-5 or even AN's).

The thing about aircraft bolts isn't that they're stronger, it's that they're more resistant to fatigue. Compare a high quality socket head cap screw that might be 180-220 ksi strength to a similar aircraft bolt (MS21250 or whatever the NAS socket head one is) and you'll see nicer threads, a smoother transition from grip to thread and a BIG radius under the head (frequently requiring a special washer). What you can't see is that the a/c bolt also has stricter requirements on material and heat-teat to ensure that it's not just hard (strong) but also tough (fatigue resistant).

I'm learning a lot about hardware from this thread! Thanks to all for the feedback, I especially appreciate the discussion about failure modes and fatigue vs ultimate stress. Hopefully I'll have some new hardware in by this upcoming weekend, really want to get this thing airborne before the deployment.

Don't forget to use the correct *washers*, too...AN970s, not AN960s.

I wouldn't have a clue as to what the potential impact of the smaller OD washers might be, because I have a constant speed prop, but they're called out for a reason, I imagine.

Rest in Peace

Out of respect for the memory of USAF Captain Mark Tyler Voss, this thread is closed. For further information, see this thread.