Ignition Switch Question

[Matthew P]

Original Ignition Switch going bad, the wafers in the tumbler are worn, new switch is $700, looking for alternative, as I understand it, for the age of the aircraft (1966) it's form, fit and function and a field approval 337 to use the following switch, can anyone tell me if they currently use this switch (with the start position) ACS Keyed Ignition Switch With Start Position A-510-2 FAA-PMA https://www.aircraftspruce.com/catalog/elpages/igswitches.php Aircraft configured with SureFly on the left, Mag on the right, SOS removed..

 

TIA,

 

Matt

[ArtVandelay]

I don’t think a 337 is necessary, sounds like a very minor mod which only requires a signature.
A 337 is for a major modification.
I’ve seen it replaced with toggle switches.

[Pinecone]

I have the switch out of my 252 available.  I went to toggle switches.

[AJ88V]

On 11/23/2024 at 11:20 AM, ArtVandelay said:

I don’t think a 337 is necessary, sounds like a very minor mod which only requires a signature.
A 337 is for a major modification.
I’ve seen it replaced with toggle switches.

I would think this would be a major mod requiring 337.  Not because the part itself is that complex, but because it's a critical, single-point-of-failure component.

Curious to hear other's opinions.

Also curious about this switch itself as a potential replacement that is affordable.  Thanks.

[EricJ]

1 minute ago, AJ88V said:

I would think this would be a major mod requiring 337.  Not because the part itself is that complex, but because it's a critical, single-point-of-failure component.

Curious to hear other's opinions.

Also curious about this switch itself as a potential replacement that is affordable.  Thanks.

FAR Part 43 Appendix A lists things that qualify as major alterations.   If it isn't on the list, it's a minor alteration.

FAR Part 1 also has a definition of Major Alteration:

Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

It's up to the installer to determine whether a modification is major or minor.   I think many would find it a stretch to consider the switch change as a major alteration, but there are those that think that changing the sun visor is a major alteration.   Whoever signs your annual inspection has the opinion that matters.

[ArtVandelay]

I would think this would be a major mod requiring 337.  Not because the part itself is that complex, but because it's a critical, single-point-of-failure component.
Curious to hear other's opinions.
Also curious about this switch itself as a potential replacement that is affordable.  Thanks.

An oil filter is critical single point of failure component. Not only do we not need a 337 if we change brands, but owners are allowed to do the work.

[ArtVandelay]

Whoever signs your annual inspection has the opinion that matters.

So does the signature take precedence over future IAs?

Lets say you take it to a new shop that needs to raise their income, can a new IA start looking over your old log entries and declaring them not airworthy?

[EricJ]

3 minutes ago, ArtVandelay said:

So does the signature take precedence over future IAs?

Lets say you take it to a new shop that needs to raise their income, can a new IA start looking over your old log entries and declaring them not airworthy?

No A&P or IA can declare a log entry unairworthy.   

Edit:   Actually they can, and I wouldn't be surprised if it hasn't been done, but there's no basis for doing so and it really doesn't make any sense to do so.   I also don't know of any consequence to anyone for doing so.

[201Steve]

Any ia that would raise a fuss over a previously installed Pma switch by a previous A&P, simply bc it wasn’t the original part number and for no other sound logical reason, is an IA that would never touch my airplane again.  Can not stand some of the idiotic interpretations that get raised by some mechanics trying to raise questions of intricate legal interpretation for something as simple as an electrical switch (Where none of said switches were ever PMA parts to begin with). Enter the lightbulb discussion. Lol
 

 

[outermarker]

I have been down this path a few years ago. I bought several used switches to take apart and swap innards and to see how it works. I also considered the rebuild kit from Bendix but even that was pricey! After I rebuilt switch worked but I still wasn't completely satisfied. So, I took the switch apart and under a microscope I saw where the key wears material away leaving you hunting for the sweet spot to where the starter will engage. 

The ACS switch your looking at uses a smaller diameter hole that will have to be considered. If you make a mounting plate for a proper fit you then have to attach the plate to the panel. There are a lot of wires behind the panel that drilling a few holes would make me nervous! So, when you consider the extra labor to mount the ACS switch that feels like it doesn't have the life cycles of the Bendix (or the price) have you really saved that much overall? I understand the ACS is certified for Cessna's so there is some quality with the switch. Since I have an Aircraft Spruce close to me, I had the advantage of actually going to the counter and comparing both switches. I left with taking a chance on rebuilding a Bendix over a new ACS for all the above reasons, mainly the smaller diameter mounting hole issues. Good Luck with your discission. 

Now I'm back considering paying that outrageous price for a new Bendix switch. It feels more robust than the ACS switch. Plus, it is an easier swap. 

[AJ88V]

19 hours ago, ArtVandelay said:

An oil filter is critical single point of failure component. Not only do we not need a 337 if we change brands, but owners are allowed to do the work.

Oil filters for certified engines carry TSO and PMA approvals.  You will not be running down to AutoZone or O'Reilly's and getting a Purolator or Fram for your Mooney.  The ACS switch is PMA for specific aircraft and the list of aircraft does not include any Mooney.

From the ACSpruce website:

• Q: Can this be installed on a PA28? [Mooney M20C]
• If your aircraft is not on the eligibility list than a field approval 337 would be required.

That said, I'm sure somebody on this forum posted that they successfully installed this in their Mooney (probably with a 337)

[AJ88V]

20 hours ago, EricJ said:

FAR Part 43 Appendix A lists things that qualify as major alterations.   If it isn't on the list, it's a minor alteration.

FAR Part 1 also has a definition of Major Alteration:

Major alteration means an alteration not listed in the aircraft, aircraft engine, or propeller specifications—

(1) That might appreciably affect weight, balance, structural strength, performance, powerplant operation, flight characteristics, or other qualities affecting airworthiness; or

(2) That is not done according to accepted practices or cannot be done by elementary operations.

It's up to the installer to determine whether a modification is major or minor.   I think many would find it a stretch to consider the switch change as a major alteration, but there are those that think that changing the sun visor is a major alteration.   Whoever signs your annual inspection has the opinion that matters.

Pretty sure an ignition switch might "appreciably affect" the powerplant operation. 

Sorry, not meaning to pick a fight at all.  @EricJ, I see you have your A&P and IA.  Your opinion certainly carries weight with me and I appreciate your points in the discussion.

This kind of stuff drives us crazy.  My IA/A&P is terrific and I would recommend his shop to anybody.  But I never know what his take on something will be.  Sometimes it's if the correct part is available - even if it's used and 50 years old - then that's the only choice, sometimes he'll adapt something approved for another aircraft, sometimes he's ok with substitution using non-approved stuff (have examples I won't put in writing), sometimes he'll just fab up a new part to keep planes in the air.  Our Mooney fleet is going to get more and more patchwork as time goes on.  I wouldn't hesitate to adapt this ACS switch (but the points made by @Outermarker about the barrel diameter are definitely worth considering).

[Matthew P]

On 11/23/2024 at 11:56 AM, Pinecone said:

I have the switch out of my 252 available.  I went to toggle switches.

Thanks, how much are you asking?

[EricJ]

1 hour ago, AJ88V said:

Pretty sure an ignition switch might "appreciably affect" the powerplant operation. 

If it can switch the mags on and off it does not appreciably affect the powerplant operation.    Changing the intake or exhaust designs so that the engine breathes less and restricts power would "appreciably affect" the powerplant operation, or a throttle cable that doesn't have enough travel to fully open or close the throttle.    A switch that still switches has no effect.

1 hour ago, AJ88V said:

Sorry, not meaning to pick a fight at all.  @EricJ, I see you have your A&P and IA.  Your opinion certainly carries weight with me and I appreciate your points in the discussion.

This kind of stuff drives us crazy.  My IA/A&P is terrific and I would recommend his shop to anybody.  But I never know what his take on something will be.  Sometimes it's if the correct part is available - even if it's used and 50 years old - then that's the only choice, sometimes he'll adapt something approved for another aircraft, sometimes he's ok with substitution using non-approved stuff (have examples I won't put in writing), sometimes he'll just fab up a new part to keep planes in the air.  Our Mooney fleet is going to get more and more patchwork as time goes on.  I wouldn't hesitate to adapt this ACS switch (but the points made by @Outermarker about the barrel diameter are definitely worth considering).

The opinion of the IA that signs off your annual is the opinion that matters.

[201Steve]

I’ve yet to find a single story of an IA being brought to justice for something like this. It doesn’t happen. Yet people act like they are about to get slapped into handcuffs at any moment. 
 

Hell, you can’t even hold a mechanic legally accountable if you wanted to. It must be the pet project of an individual enforcer and even then, never heard of a single citation. 

[PT20J]

IAs I’ve dealt with are not overly concerned about enforcement. However, they take their responsibility to follow the rules seriously and genuinely try to do what they believe is correct. They wouldn’t sign a check if there wasn’t money in the bank, and they don’t want to sign a logbook if they think the maintenance isn’t legit. The problem is that a lot of the rules are subject to interpretation and reasonable individuals can have different interpretations. 

[jamesm]

Is there any disadvantages of  have  gone the a 337 route?  I was looking from  Garmin G5 (G3X)/ GFC500 and all other add on (magnetometer GMU11, GAD13, GAD29,etc etc)  to make an entire "system" prospective. So the Bendix  system would be 2 Magneto's (one with retard breaker) ,Push to start ignition switch and the shower of sparks starting vibrator  and I went to the Electroair  (cheap quality) rocker switches and push to start button since it had a STC.  My rational was that I did it thinking that it would CYA if I ever sold the airplane or question by FAA inspector (highly unlikely). Plus I was thinking since the Bendix magneto system which included the SOS and ignition switch Bendix system which of course it has been bastardize when I went to SureFly Ignition several years ago.

Just Curious,

James '67C

[Justin Schmidt]

On 11/23/2024 at 9:23 AM, Matthew P said:

Original Ignition Switch going bad, the wafers in the tumbler are worn, new switch is $700, looking for alternative, as I understand it, for the age of the aircraft (1966) it's form, fit and function and a field approval 337 to use the following switch, can anyone tell me if they currently use this switch (with the start position) ACS Keyed Ignition Switch With Start Position A-510-2 FAA-PMA https://www.aircraftspruce.com/catalog/elpages/igswitches.php Aircraft configured with SureFly on the left, Mag on the right, SOS removed..

 

TIA,

 

Matt

I have an ignition cylinder if you want to go that way

[ArtVandelay]

I thought they had a rebuild kit for these switches, much cheaper than a new switch?

[outermarker]

They do, three springs and caps for about half the price of a new switch. Bendix is really proud of their switch...the price reflects that pride!

[Igor_U]

I think Bendix rebuilt kits are very difficult to find new, at least they were few years ago when I was looking. I was lucky as an MS member had one for sale for a great price. I rebuilt my swithc and have had no issues whatsoever. 

You might want to search Ebay or other Parts sales (BCA used to have them) if one pops up. Good luck. 

[ProtoFly]

Why not go with something like the Electroair Ignition Panel?

Gets rid of the AD...

https://www.aircraftspruce.com/catalog/pnpages/08-17142.php