Just to start a fire :-) Back Up AI

[cliffy]

All engine drive pads have torque and overhang weight limits. They can be dug up with enough work. 

Staying within those limits precludes hanging something on the pad that has a way high torque value for the gear train underneath or is way to heavy for the over hang. 

There is a guy that can do the engineering. He has a license to engineer ANY aviation engine package. One smart dude!

Edited June 28, 2022 by cliffy

[EricJ]

13 minutes ago, 201Mooniac said:

I couldn't even get Lasar to reply to my request to do the same with my plane even though they did it here.  I guess there was concern that without a Lycoming based STC there would be structural data needed for the vacuum pad housing (or so I was told).

The STC cited in the 337 for the PA-32 is on a Lycoming engine, an IO-540, which has a similar accessory case structure as an IO-360 (essentially the same).  The experimental guys do it all the time.   I help a friend with his Brazov, which has a Lycoming IO-540, which has a backup B&C mounted on the vacuum pad.   

But, yeah, I'm surprised that that's all they used for approved data at the time, but it got the stamp from the SAC FSDO, so it's golden.   Maybe that guy retired or something. 

 

[Guest]

Basic Aircraft Products makes an STC’d wind driven backup alternator for many airframes including Mooney.

https://www.basicaircraft.com/home

Clarence 

[hammdo]

And out of stock ;o)...

-Don

[Mooney in Oz]

2 hours ago, EricJ said:

The STC cited in the 337 for the PA-32 is on a Lycoming engine, an IO-540, which has a similar accessory case structure as an IO-360 (essentially the same).  The experimental guys do it all the time.   I help a friend with his Brazov, which has a Lycoming IO-540, which has a backup B&C mounted on the vacuum pad.   

But, yeah, I'm surprised that that's all they used for approved data at the time, but it got the stamp from the SAC FSDO, so it's golden.   Maybe that guy retired or something. 

 

I know it doesn’t help you folks in the US, but I had mine approved with the Australian authority based on this STC. It is one of the best additions I’ve made to my Mooney.

[jetdriven]

Can’t use an STC as approved data for a field approval.  However you can hire a DER.  Not being able to replace a vacuum pump with a alternator is patently ridiculous. 

[Mooney in Oz]

4 hours ago, Marauder said:

Illegally.

My guess they got a field approval. I approached Philly FSDO about installing one in my Mooney. I would have better luck asking the guy if I could date his wife.


Sent from my iPhone using Tapatalk Pro

Be careful what you wish for 

[MikeOH]

14 minutes ago, jetdriven said:

Can’t use an STC as approved data for a field approval.  However you can hire a DER.  Not being able to replace a vacuum pump with a alternator is patently ridiculous. 

While I think redundant alternators is a good thing, I'm going to be heretical and say I really like independent backup systems: i.e. BOTH vacuum and electric.  An extra alternator does NOT ensure something else won't take out the electric system.  As an EE for many decades I just don't trust all those electrons that much

[jetdriven]

Just now, MikeOH said:

While I think redundant alternators is a good thing, I'm going to heretical and say I really like independent backup systems: i.e. BOTH vacuum and electric.  An extra alternator does NOT ensure something else won't take out the electric system.  As an EE for many decades I just don't trust all those electrons that much

Which is why you have a backup battery on your standby AI.  Or pair of G5s etc.   That’s your third and fourth independent source.  There’s actually something to be said about a lifesaver iron gyro with a backup battery.  It’s not electronic 

[BobbyH]

2 minutes ago, MikeOH said:

As an EE for many decades I just don't trust all those electrons that much

Those loose electrons will always find a path out, the path of least resistance. 

[MikeOH]

19 minutes ago, jetdriven said:

Which is why you have a backup battery on your standby AI.  Or pair of G5s etc.   That’s your third and fourth independent source.  There’s actually something to be said about a lifesaver iron gyro with a backup battery.  It’s not electronic 

Sure, you can keep stacking on levels of redundancy and increase reliability, no doubt.  I've also seen spikes induced by both internal and external (e.g. lightning) events take out the electronics (I've seen this in other other electronic systems; no personal experience with aircraft, but I wouldn't rule it out), which would include ANYTHING connected to power like those oh so loved G5s.  Granted, a completely standalone 'iron gyro' NOT connected to the aircraft busses would be immune to that.

All of this because of the hatred of vacuum systems.  I just find it a curious hypocrisy that we hear the best money spent is on frequent recurrent training (partial panel anyone?), yet spending money on all electric is pushed because pilots can't fly partial panel??

I think the venturi vacuum is an excellent back-up idea; two completely different and independent systems sounds pretty smart and a lot cheaper than cramming a couple of extra fancy electronic gyros in the panel.

No one ever talks about the downsides of these battery backed gyros: what are the ICA requirements?  Sure, it's probably no worse than for an ELT, but it's one more hassle and maintenance item to deal with.  And, what about glitches? You know, BSOD stuff that you'll need to reboot...can you do that without cycling the master while in IMC?  How long does it take?  Or, are you and the manufacturer going to guarantee that can "never happen?". 

For me, when it comes to backup, the simpler the better.  IMHO

[N231BN]

Can’t use an STC as approved data for a field approval.  However you can hire a DER.  Not being able to replace a vacuum pump with a alternator is patently ridiculous. 

You absolutely can, if you have a permission letter from the STC holder. B&C will gladly supply one if you buy one of their systems.

In 2020 I got a field approval for a R182 using B&C's STC for a PA-32 (engine commonality) and a previous 337 for a 182Q. The FA for the 182Q used the Bonanza STC for the engine modification.

I could make a comment about a FSDO inspector refusing to consider a safety improvement, but "mama said..."

[cliffy]

Find me an FAA Inspector today that even knows how a  venturi gyro system works and I buy lunch!

[N201MKTurbo]

2 minutes ago, cliffy said:

Find me an FAA Inspector today that even knows how a  venturi gyro system works and I buy lunch!

Hay, my 56 Cessna has two! One for the AI and one for the DG. I think one would run both. No vacuum regulator, it hits almost 10 inches in flight. I can get 3 inches just from prop blast.

All the calculations for  venturis is in 43-13. I had to figure it out for my IA test. 

[cliffy]

Question- How do you parallel the 2 generators?

Or is the system so complex now because you have to disconnect 1 gen and then turn on the other?

What do you have to download to keep within the 2nd gens output limits?

More complexity = more prone to failure, more mistakes happening in a stressful time. 

[cliffy]

1 minute ago, N201MKTurbo said:

Hay, my 56 Cessna has two! One for the AI and one for the DG. I think one would run both. No vacuum regulator, it hits almost 10 inches in flight. I can get 3 inches just from prop blast.

All the calculations for  venturis is in 43-13. I had to figure it out for my IA test. 

There are 3 venturis available

a 2" small one just for 1 turn and  bank needle

a 4" one for just 1 gyro

a 10" one that runs both Ai and DG gyros but does really need a regulator valve as too much suction can drive the gyro spool at too high a rotational speed.

In my C-140 I had one  10" and my gyros were usually always erect by 200" AGL

[N201MKTurbo]

8 minutes ago, cliffy said:

There are 3 venturis available

a 2" small one just for 1 turn and  bank needle

a 4" one for just 1 gyro

a 10" one that runs both Ai and DG gyros but does really need a regulator valve as too much suction can drive the gyro spool at too high a rotational speed.

In my C-140 I had one  10" and my gyros were usually always erect by 200" AGL

I have been leaving them caged until I’m at about pattern altitude, then uncaging them and set the DG. They both work fine after that.

both venturis are about 3 inches in diameter and about 10 inches long.

Edited June 29, 2022 by N201MKTurbo

[EricJ]

9 hours ago, cliffy said:

Question- How do you parallel the 2 generators?

Or is the system so complex now because you have to disconnect 1 gen and then turn on the other?

What do you have to download to keep within the 2nd gens output limits?

More complexity = more prone to failure, more mistakes happening in a stressful time. 

A backup alternator just has the regulator set at a lower output voltage than the primary, usually about halfway to the battery voltage.   e.g., A 14V system with a 12V battery has the primary voltage regulator set to 14V and the backup regulator set to 13V.   If the primary fails the backup sustains the voltage at 13V, which is still enough to provide power and prevent the battery from draining assuming it is not overloaded (so load shedding will likely have to happen if the backup can't sustain the load).

This also provides relatively easy means to indicate that the primary has failed (Voltage<13.5V or so), and total failure (V<12.5V or so).

Those are just example voltages, but that's the idea of how it works.   So it's not the same as paralleling a system, since the backup doesn't come on-line unless the primary fails.

[cliffy]

But wouldn't one still have to download the main buss to stay below at back up gen output?

[jetdriven]

Yes, you have to load shed the main bus down to 30 A or so to get the standby alternator to carry all of the load. In modern aircraft with LED lighting and electronics, that’s not too hard to do.