BRITTAIN AUTOPILOT TROUBLESHOOTING - TECH SUPPORT

[DCarlton]

For those of you still operating a Brittain wing leveler or autopilot, Kevin Westbrook (former Brittain technician for over 30 years) is willing to help over the phone with troubleshooting.  He has helped me trace a recent problem to the DG.  I'm trying to keep my Brittain system and in particular the EVT turn coordinator operational for as long as possible.  Kevin may be reached at 918-521-5139.  If a turn coordinator needs overhaul, it can be serviced through Porter Strait Instrument Co in Tulsa.  I asked Kevin if it was OK to post his phone number and he said it was fine.  

[Matt Ward]

Does anyone know of an individual who can service the altitude hold components of the Brittain APs?  Kevin doesn't work on this and I'd like to get some work done on mine. Thanks.

 

[0TreeLemur]

2 minutes ago, Matt Ward said:

Does anyone know of an individual who can service the altitude hold components of the Brittain APs?  Kevin doesn't work on this and I'd like to get some work done on mine. Thanks.

 

Sadly, Cecilia Henderson of Brittain told me that the knowledge required to service those systems passed along with her brother Jerry couple of years ago.  She knows of nobody else who can service that equipment.  Wish I had better news for you.   If someone else knows of some expertise out there, please share!

Fred

[takair]

3 hours ago, Matt Ward said:

Does anyone know of an individual who can service the altitude hold components of the Brittain APs?  Kevin doesn't work on this and I'd like to get some work done on mine. Thanks.

 

PM sent.

[Shadrach]

18 hours ago, DCarlton said:

For those of you still operating a Brittain wing leveler or autopilot, Kevin Westbrook (former Brittain technician for over 30 years) is willing to help over the phone with troubleshooting.  He has helped me trace a recent problem to the DG.  I'm trying to keep my Brittain system and in particular the EVT turn coordinator operational for as long as possible.  Kevin may be reached at ***-***-****.  If a turn coordinator needs overhaul, it can be serviced through Porter Strait Instrument Co in Tulsa.  I asked Kevin if it was OK to post his phone number and he said it was fine.  

Maybe consider posting Kevin’s number in a way that cryptic to prevent bots from adding it to a list. Like so:

nine 1 eight - fife two 1 - 5 1 tree 9

[211º]

For the altitude control system, I was wondering if it would be possible to find something on line to its plans/details. I was thinking the US Patent office - to understand the theory of it.  But a 30 minute minute search confirmed that the US Patent Office site is not my forte.

Anyone have any other ideas?

[0TreeLemur]

29 minutes ago, 211º said:

For the altitude control system, I was wondering if it would be possible to find something on line to its plans/details. I was thinking the US Patent office - to understand the theory of it.  But a 30 minute minute search confirmed that the US Patent Office site is not my forte.

Anyone have any other ideas?

That is a great question.  I've thought about doing the same, but haven't yet.   Please share what you find.   I'm guessing that the Brittain system has its roots in WW-II aircraft or perhaps before that.  Anybody know that history?

Thanks to some help from MS members, I've assembled all the parts for the altitude/pitch hold.  I have two each of the altitude hold and pitch hold modules.  One of them should work!  My plan is to bench test before installing in the aircraft.  I've designed a bench test apparatus and am starting to assemble the needed parts for the test rig.  I should be able to test both control modules.

I need a bench vacuum source.  Just curious, does anyone know off hand how much air flow a standard suction gyroscopic instrument requires at 5" Hg suction pressure?  That will help me select a vacuum pump.  It seems like rigging a used Rapco vacuum pump to work off an electric motor with a pulley system would be a PITA given its splined shaft.  How fast does a Rapco pump turn at 2500 rpm engine speed? 

Have you seen the Brittain Altitude Hold Installation instructions?  I think they exist in the MS downloads section in a big zip file containing Brittain stuff.  If not PM me and I'll send it to you.

[carusoam]

Rapco has a ton of information about their pumps...

Unfortunately, the rpm they operate at... seems to be covered in the applications guide based the engine they are attached too...  which is a set gear ratio that doesn’t change...

So... we know the volume of the pump... but not it’s revolutions per minute... Doc may know, as would Alan, and probably every mechanic...

 

The other place we could look... we could find preciseflight who bolts an electric motor to the back of a vac pump...

https://www.aircraftspruce.com/catalog/pnpages/10-00268.php?gclid=Cj0KCQjwo-aCBhC-ARIsAAkNQis_vn4qFWr7SEAv3o6y3fAhVVx208VFkB6IRoUSAGj7GhrUlicEZZUaAtAnEALw_wcB

 

The preciseflight website doesn’t seem to have the back-up vac system anymore... hmmm....

 

https://preciseflight.com/general-aviation/

Best regards,

-a-

[0TreeLemur]

Of interest, a NASA Tech. Note D-3970 published May, 1967, testing the utility of the PC system in assisting non-instrument rated pilots in flight in the case of inadvertent flight into IFR conditions.   Interesting to see a Mooney referred to as a "test vehicle".   Oddly, the words "Mooney", "Brittain", or "PC" don't appear in this TN.  I guess they didn't want to appear to endorse any particular product or brand.    Experienced test pilots conclude that the PC system significantly reduced flight workload, and results showed automatic recovery from the graveyard spiral.

https://books.googleusercontent.com/books/content?req=AKW5Qaf63BDkGtbmb6iECe9nOJOykPLCHYZCGr9V0pW1EDbU_ITlHmmoy5sp8UOIfbt08BwtK1bca6a98i67Z5U_k8Fsfp-ZJzeAoaCMtfw_5SwVWpw7OWWYIguRjr95RGmuk9f5B5FmjLwABJFyuOtpTK2XCiWsaAG0nkOhyns7FGmmC6VeDO7MZsTdzlw18nTTUbaMKHyPfs8eBItFPsyte6wj88lYmz_1qZSVfyk8dh-qdz9GyAOSGx1_NBDPseUSdblER_qyj5otLSLrBJvCZJMdwjtjNg

Short on references too.

[takair]

7 hours ago, 211º said:

For the altitude control system, I was wondering if it would be possible to find something on line to its plans/details. I was thinking the US Patent office - to understand the theory of it.  But a 30 minute minute search confirmed that the US Patent Office site is not my forte.

Anyone have any other ideas?

I recently installed an altitude hold system and picked up some spare modules to help reverse engineer the set up. It was worth the investment. I have pictures of the internals and general feel for how they interact. I started to write a white paper on the theory so I could refer to it in the future, but not quite done.....need to add the pictures.  The hard part of the system is that it relies on calibrated leaks to work, so it is difficult to test and know what one is seeing.  The mechanism is quite intricate as well. Until I finish the paper, I am more than happy to speak to anybody about my findings and share info. Likely easiest to do by phone. There are a few settings that are user accessible. Don’t change them until we speak. Some of them can cause irreversible damage. The system is generally maintainable but for the rubber parts. It seems the diaphragms can  be individually tested for leaks. If they leak....that is a problem since I’ve not been able to find a ready source.....I have one system in that condition now.  Perhaps with more of us looking we can find sources of some of these parts. By the way, a common mis-perception is that there is a pendulum inside. That is not the case. G forces are managed by calibrated weight on the diaphragm. Genius. 

[takair]

7 hours ago, 0TreeLemur said:

That is a great question.  I've thought about doing the same, but haven't yet.   Please share what you find.   I'm guessing that the Brittain system has its roots in WW-II aircraft or perhaps before that.  Anybody know that history?

Thanks to some help from MS members, I've assembled all the parts for the altitude/pitch hold.  I have two each of the altitude hold and pitch hold modules.  One of them should work!  My plan is to bench test before installing in the aircraft.  I've designed a bench test apparatus and am starting to assemble the needed parts for the test rig.  I should be able to test both control modules.

I need a bench vacuum source.  Just curious, does anyone know off hand how much air flow a standard suction gyroscopic instrument requires at 5" Hg suction pressure?  That will help me select a vacuum pump.  It seems like rigging a used Rapco vacuum pump to work off an electric motor with a pulley system would be a PITA given its splined shaft.  How fast does a Rapco pump turn at 2500 rpm engine speed? 

Have you seen the Brittain Altitude Hold Installation instructions?  I think they exist in the MS downloads section in a big zip file containing Brittain stuff.  If not PM me and I'll send it to you.

I took an old vacuum pump and used a RAPCO rebuild kit so I could test on aircraft. The gyro requires quite a bit of flow, but can’t recall the numbers. The rest of the system.....the servos and alt hold, rely purely on vacuum and a little flow to overcome the tiny calibrated leaks. Here is a picture of my pump assembly built up in an old snap on tool box. Would offer to ship, but it is really heavy. Probably could source someone’s bad pump here on Mooneyspace. 

[211º]

6 hours ago, 0TreeLemur said:

Of interest, a NASA Tech. Note D-3970 published May, 1967,

Wow - that ground track on the last page of the report! (for others that didn't look at the report - it shows a desired flight path, the actual flight path of a non-instrumented rated student with the PC system on and off).

[211º]

8 hours ago, 0TreeLemur said:

I need a bench vacuum source.  Just curious, does anyone know off hand how much air flow a standard suction gyroscopic instrument requires at 5" Hg suction pressure?  That will help me select a vacuum pump.  It seems like rigging a used Rapco vacuum pump to work off an electric motor with a pulley system would be a PITA given its splined shaft.  How fast does a Rapco pump turn at 2500 rpm engine speed? 

Have you seen the Brittain Altitude Hold Installation instructions?  I think they exist in the MS downloads section in a big zip file containing Brittain stuff.  If not PM me and I'll send it to you.

Yes to the installation instructions - those are useful. What I'd really like to see is a section-view of both the pitch control and altitude control boxes.

I look forward to hearing/reading about your results.

[cliffy]

I was informed a few years ago the biggest problem with the alt hold system today is finding a good "eyeball" to show trim condition. There are two different ones. One is "brass housing the other is black plastic One is way better than the other. If the lines do not match up static then the eyeball is junk. 

The next hump is what is the legality to install, STC usage ,etc. ?

Edited March 24, 2021 by cliffy

[takair]

9 minutes ago, cliffy said:

I was informed a few years ago the biggest problem with the alt hold system today is finding a good "eyeball" to show trim condition. There are two different ones. One is "brass housing the other is black plastic One is way better than the other. If the lines do not match up static then the eyeball is junk. 

The next hump is what is the legality to install, STC usage ,etc. ?

Cecilia has been wiling to share STC paperwork including permissions.  I installed and signed mine off last year.   After much tinkering it works fantastic.

[cliffy]

9 minutes ago, takair said:

Cecilia has been wiling to share STC paperwork including permissions.  I installed and signed mine off last year.   After much tinkering it works fantastic.

That's pretty good!  Nice to know

[Igor_U]

7 hours ago, takair said:

Cecilia has been wiling to share STC paperwork including permissions.  I installed and signed mine off last year.   After much tinkering it works fantastic.

Is she still answering on Brittain emails?

I tried twice few months ago (using link on their website) and never got the answer. 

[takair]

14 minutes ago, Igor_U said:

Is she still answering on Brittain emails?

I tried twice few months ago (using link on their website) and never got the answer. 

Reports are that she is still answering the phone.  Would try to call the number.  She was really helpful to me last year, but I know a couple of emails slipped by.  

[Raymond J1]

I wanted to publicly thank Cecilia Henderson and Kevin Westbrook for their help in restoring and return to sevice my BI 603 controller, rebuilding the BI 502 harness and overhauling the BI 102 heading sensor. Without them, the following video would have been simply impossible to do.

[yvesg]

Raymond, c’est quoi au juste ce bidule?

Yves

[Raymond J1]

4 minutes ago, yvesg said:

Raymond, c'est quoi au juste ce bidule?

Yves

This is the servo motor at the end of turn coordinator, driven by the BI 603 controller. For the video, I simulated a capture of HDG from + to - 30 ° of the road, which makes deflected the servo motor up to the rate 1 of turn (support on the stops).

[carusoam]

Great video and pirep of the Brittain people... JR!

Thanks for sharing the details...

Best regards,

-a-

[DCarlton]

On 3/24/2021 at 12:57 PM, takair said:

Reports are that she is still answering the phone.  Would try to call the number.  She was really helpful to me last year, but I know a couple of emails slipped by.  

Kevin Westbrook can be reached at 918-521-5139.   Cecilia Henderson is at 918-836-7701.  Kevin helped me last month over the phone.  

[RLCarter]

On 3/24/2021 at 6:09 AM, takair said:

I took an old vacuum pump and used a RAPCO rebuild kit so I could test on aircraft. The gyro requires quite a bit of flow, but can’t recall the numbers. The rest of the system.....the servos and alt hold, rely purely on vacuum and a little flow to overcome the tiny calibrated leaks. Here is a picture of my pump assembly built up in an old snap on tool box. Would offer to ship, but it is really heavy. Probably could source someone’s bad pump here on Mooneyspace. 

Like a lot of things, this is one that I have been meaning to make for several years, I have the pump but have been putting it off mainly due to over complicating the coupler, but you seem to have overcome that issue, I like it. What info would you be willing to share on you build?

[jamesm]

7 hours ago, Raymond J said:

I wanted to publicly thank Cecilia Henderson and Kevin Westbrook for their help in restoring and return to sevice my BI 603 controller, rebuilding the BI 502 harness and overhauling the BI 102 heading sensor. Without them, the following video would have been simply impossible to do.

So Raymond is that the mechanical circuit equivalent to electronic comparator circuit for heading ?