cliffy

Starting Battery Relocation to Tailcone

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Starting to relocate my battery to the tailcone next week. According to 43.13 it is highly recommended to use factory locations and parts if this is done. Lucky for us this is easily done.  I secured the factory parts (battery box and two side brackets) and have attached pics below. 

Basically, the left bracket attaches to the rear baggage bulkhead right at the pass through hole for all the wiring going aft (pic). There was a small aluminum doubler attached to the pass through hole that I just drilled off. The left bracket fits over this hole and attaches at several extra rivet locations, 

The battery box and right bracket attach using all of the original rivets and then some more. It looks like a two man riveting job OR I could use CherryMax at a much higher cost. I will also probably go to AN470 AD -4 rivets instead of the installed -3s as some of the holes do not precisely line up. 

I'll use the factory specified #2 electric cable to run forward (along the left sidewall) to the buss bar. The new solenoid will be mounted in back next to the battery.  

I'll update this as I go along. Not in a big hurry. 

Batery box tail left bulkhead hole.jpg

Battery box tail left bulk head hole with box.jpg

Battery box tail left bracket.jpg

Battery box tail 3.jpg

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How are you planning on getting the approval done?

For any small project, the difference in cost between solid and Cherrymax rivets is silly.  We're talking, what, about $30-40 of rivets?  Unless you're building a whole tailcone, or you're very comfortable and proficient setting solid rivets, I'd vote just using Cherrymax rivets

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Interesting....

Things to add to the thoughts list...

1) where does the drain go to? A new hole? (I’ll have to look at my own...)

2) Get the ground power plug parts if you can...? (I think the hole aligns with/in the big access panel...)

3) any thoughts of using a BatteryMinder..? (Wired up within the GP plug area may be helpful...)

4) Fly often enough, use a Concorde sealed battery, and skip this list?   :)

PP thoughts only, not a mechanic...

Best regards,

-a-

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1) the drain holes - one (the outlet for venting ) goes through a recessed trough in the belly and the inlet is just an angled cut on the drain tube. For sealed batteries its not needed. 

2) Not going to use a Grd Plug. I think its silly and dangerous. If the battery is dead I ain't going flying with a jump start and a dead battery. I'm not going to quick charge a battery at anything oven a 10 hour rate. The access panel is easy to remove and so is the battery for charging per the makers requirements. 

3) Don't need it. I fly enough and I have a heated hangar right now

4) I'm going Concord sealed after talking to the guy from Concord at MooneyMax this year. This also negates any need for putting the drain system in. 

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I would probably put the vent system in just for cooling aspect.   I got some battery cable crimpers and cutters for $29 off amazon for a boat project. they have the lugs too

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@cliffy if you want to go a little more CB on this install I have a used Concord battery that was mistakenly replaced when I had starting issues. I’ll sell it to you pretty cheap and deliver it to the summit if you’re going. 

Edited by MIm20c

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Unfortunately not going to Summit as I'm on an Alaskan Cruise then.  But thanks anyway I appreciate the offer. 

 

BTW,  its really not a CB project but those are my initials :-)

Edited by cliffy

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The approval is easy as its all explained in 43.13 on how to relocate a battery. 

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Had the battery under the back seat in my Cherokee.  Big voltage drop to go that distance, if the battery got even a bit weak it was murder to get started in the cold.  I would think very carefully before I did such a modification.

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Obtuse question:  What are the advantages of moving to the tail?  I guess accessing r without getting killed by the prop for a jump start is easier.  

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12 hours ago, cliffy said:

The approval is easy as its all explained in 43.13 on how to relocate a battery. 

I guess I was thinking more about wiring and electrical loads.  I'm guessing there's no cabling set up right now to handle the maximum current load from the tailcone to the front?  If it was in the nose before, I imagine all the large-gauge cables were up front.  An IA might look at changing the battery cables as a major modification?

Edited by jaylw314

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For me the biggest advantages are moving the CG aft 1.2 inches and making getting to the rear of the engine (especially the left mag LOTS easier). I need the extra aft CG position for fuel weight. I have a heavy 3 blade on the front! Secondarily will be battery life which I think will be greatly improved by less vibration and heat. As I stated, I'm not a big fan of jump starts. It is dangerous in my opinion due to charging off into the blue with essentially a dead battery and improper charging of a dead battery leading to loss of battery capacity. What happens if you jump start and lose the generator 10 mins into the flight? Can you get the gear down without using alternate means? How about flaps? How about radios? IFR?

As an aside- if I were to do lots of IFR I would also do a battery capacity check every year. That's also an ICA requirement but that's a discussion for a different time. I'd also know how to down load the CBs fast so I had every advantage in battery time if I lost the generator in flight IFR. How long will your battery power what you need in flight? You might really want to know this if you go IFR a lot. Try running everything for 30 mins on the ground without the engine running and then see what your unloaded battery voltage is- if it makes it 30 mins. Your battery is your life line IFR. One battery, one generator (in most cases), after that you're on your own. Just because it started the airplane doesn't mean it will last a long time in the air. Remember, the last time you came out and found your battery wouldn't turn the engine over enough to start, it did just fine one flight before.

An item to think about, in most jet airliners, battery capacity is listed as 30 mins only IF you get down to DC power only. That means get your butt on the ground as fast as you can because from 35,000 feet your going to use almost all of that time getting down to the ground. I used to teach that if that happens declare the emergency and get to the nearest suitable airport as fast as you can.

If one looks at 43.13 one will see that it is recommended to use factory locations and factory parts to make approval easier. I am using factory locations, attachment methods and parts. A 337 will suffice as a major alteration. Yes, an IA is needed to sign off the 337 but its still easy to do. 

Electrical loads? All one has to do is duplicate what Mooney already has done in hundreds of other Mooneys (which if one is smart that is what one would do in a Mooney). Take a look at the wiring diagrams and see what wire sizes are used and duplicate that. Also a new master solenoid is being installed in the back so there will be no loss on old contacts if the original solenoid was used (50 year old contacts mean lots of wear there). We are not talking rocket science here although, I knew a real for God rocket scientist once :-) Years ago some airplanes came with aluminum wiring that caused high resistance in connections and loss of battery voltage making for hard starts under heavy loads. Not used anymore. It all  has to do with proper wire size and good connections and a well cared for battery. How many Mooneys have the battery in the back with NO problems? :-) :-)

 

 

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4 minutes ago, cliffy said:

If one looks at 43.13 one will see that it is recommended to use factory locations and factory parts to make approval easier. I am using factory locations, attachment methods and parts. A 337 will suffice as a major alteration. Yes, an IA is needed to sign off the 337 but its still easy to do. 

Electrical loads? All one has to do is duplicate what Mooney already has done in hundreds of other Mooneys (which if one is smart that is what one would do in a Mooney). Take a look at the wiring diagrams and see what wire sizes are used and duplicate that. Also a new master solenoid is being installed in the back so there will be no loss on old contacts if the original solenoid was used (50 year old contacts mean lots of wear there). We are not talking rocket science here although, I knew a real for God rocket scientist once :-) Years ago some airplanes came with aluminum wiring that caused high resistance in connections and loss of battery voltage making for hard starts under heavy loads. Not used anymore. It all  has to do with proper wire size and good connections and a well cared for battery. How many Mooneys have the battery in the back with NO problems? :-) :-)

AFAIK, to get a 337 for a major modification, you need FAA approved data such as an STC (or DER approval?).  43.13 only provides FAA acceptable data for minor modifications.  You might convince someone that the design specs of other type aircraft of the same make might represent acceptable data, but I don't know what the odds are, and that still doesn't help for a 337.  So I think you either have to convince the IA that you use at annual that this is a minor modification, or find some source of approved data for a major modification...

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Cliffy is the IA he uses for his Annuals, so no problem there.

And honestly this modification is really just a minor alteration based on the FAA's own wording.  Putting it on a 337 is probably a good idea just for documentation purposes. Everything he's using are Mooney Factory parts that are installed on every fuel injected Mooney starting with the 1964 M20E, so that isn't a problem either.

The only thing I haven't heard mentioned is doing a forward and aft limit weight and balance for both full and empty tanks and documenting that on the 337.  But that shouldn't be a problem either because of his 3-blade prop.

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AC 43-210A

"Alteration data from the current edition of AC 43.13-2, Acceptable Methods, Techniques, and Practices—Aircraft Alterations, as approved data for major alterations for nonpressurized areas of civil aircraft when the AC chapter, page, and paragraph are listed in block 8 of FAA Form 337, when the user has determined that it is: • Appropriate to the product intended to be altered; • Directly applicable to the alteration being made; and • Not contrary to the airframe, engine, propeller, product, or appliance manufacturers’ data."

And I've already run the W&B many times

Also here is a very good description of just what a major or minor alteration might be (moving the battery can reasonably be classified as a "minor alteration" in a Mooney

https://www.aopa.org/news-and-media/all-news/2014/october/22/aircraft-maintenance-major-vs-minor-alterations-part-2

Edited by cliffy
added text
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3 hours ago, jaylw314 said:

AFAIK, to get a 337 for a major modification, you need FAA approved data such as an STC (or DER approval?).  43.13 only provides FAA acceptable data for minor modifications.  You might convince someone that the design specs of other type aircraft of the same make might represent acceptable data, but I don't know what the odds are, and that still doesn't help for a 337.  So I think you either have to convince the IA that you use at annual that this is a minor modification, or find some source of approved data for a major modification...

Since he is not cutting a wing spar.   and the approved data is another plane from Mooney in the M20 type.   and the battery location is not in the Type Data Sheet, but the battery type is....

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2 hours ago, Andy95W said:

Cliffy is the IA he uses for his Annuals, so no problem there.

That was the part I was missing!  No problem convincing yourself to sign off on future annuals :D

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I have an IA in the hangar visiting from out of state and he looked at it and said HE wouldn't have any issue with it either. 

AND I do occasionally have another shop do my annual just so I don't miss anything.

AND if needed-   "Alteration data from the current edition of AC 43.13-2, Acceptable Methods, Techniques, and Practices—Aircraft Alterations, as approved data for major alterations for nonpressurized areas of civil aircraft when the AC chapter, page, and paragraph are listed in block 8 of FAA Form 337

Edited by cliffy
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I see this all the time. You’re calling it a minor alteration (I agree, fwiw) 

But you’re  signing a form 337 which at the very top says “Major alterations”. So why not just skip the form 337 and make it a log entry. 

16194B58-547D-4507-A500-7575177DF924.png

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28 minutes ago, jetdriven said:

I see this all the time. You’re calling it a minor alteration (I agree, fwiw) 

But you’re  signing a form 337 which at the very top says “Major alterations”. So why not just skip the form 337 and make it a log entry. 

 

Byron, I felt the exact same way and would constantly question my FSDO at IA renewal seminars about it.  They finally convinced me by saying that putting it on a 337 makes it a permanent part of the aircraft records so even if the logbooks are lost, there is still a record of it.  Should you put every minor alteration on a 337?  No.  But a fairly complex one like moving the battery location-  probably.

And as easy as it is to fill out the PDF, why not?

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Because the form is for major alterations. This project can’t be both, it’s either major or minor 

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