Speedbrakes failed after only 31 years of use

[BobAustin]

They just failed to operate.  Called Precise Flight and they said send them in for repair $$$.    I think a little diagnosis is in order first...

They were installed in 1985 when I bought the M20J at Mooney.  They have been lubed at each annual (per David at DuGosh).

Question is:  are these vacuum operated or electric as were latest models ? David said  could be hole in the vacuum actuator ???

 

 

 

 

[carusoam]

Pp thoughts....

1) Electric ones are more independent of each other.  They each have an electric motor and a clutch that has tendency to wear.  They are really easy to test while in the hangar.  They typically fail independently.

2) the vacuum powered ones have one source of Vacuum, and are more difficult to test in the hangar, unless you have the alternate vac source....

3) Both styles operate off of one switch..?  Verify if the switch needs to be cleaned every thirty years or so...?

Clearly not mechanic quality ideas.

Best regards,

-a-

[StevenL757]

I'd start with knowing whether power is actually getting to the speedbrakes.  Have you connected an external power supply to your plane and tested on the ground?  Can you hear the motors of each speedbrake run, or try to run when you deploy them in the cockpit?  Are you popping a breaker (sounds like 'no')?

Also, your checklist for annual includes an item to have your speedbrakes inspected every 200 hours.  Has this been getting done?  If so, have there been any observations that cause concern?

[LANCECASPER]

If these were installed 31 years ago I think they are vacuum operated.

[StevenL757]

Interesting.  I started typing about that earlier but deleted.  If Bob does indeed have vacuum brakes, I'd think that a leak would produce a partial operation as opposed to a hard failure.  Thoughts?

[BobAustin]

The speedbrakes worked perfectly on the next to last flight..then failed completly when I was crusing along at 13,000 prior to decent in Austin/Lakeway (900') .  Was enjoying the cool air prior to decending into 101 at 3R9.  Of course I delayed as long as possible, cancelled IFR so as to enjoy the coolness.  Oops... getting down was not so easy w/o speedbrakes.  I know I should have slowed to gear speed, lowered then...etc

Going to take to DuGosh this week to analyze...Will report back findings

[N5756v]

That's how mine failed on my 84 231. All at once , working good on the last flight then just nothing . The bad news is the vacuum pod is where the leak is usually and I have been looking for a pod for almost a year . The vacuum pod is made by Britten industry's in Oklahoma if you need the contact info just drop me a pm . Last I heard from Britten is they were hoping to have some made by the end of this year

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[co2bruce]

31 years, that's it. What pieces of crap. 

[Oldguy]

The vacuum operated speed brakes will have a cable running from each speed brake to the vacuum pot. If you take off the inspection cover under one of the brakes, you will either see the cable or a wiring harness (electric). But a failure on both if they are electric would have to be something common like a breaker, button or something. Most likely the vacuum pod like mentioned elsewhere. 

[BobAustin]

UPDATE:

Yes they are vacuum operated.  Problem was leak in the vacuum pot bellows.

No, Brittian did not have a replacement and no clue as to when/ever they will have one

Model: BI 706,  p/n 20412-4-0

Called Precise Flight, Paul Lowen etc no joy yet.

Anyone converted vacuum speedbrakes to electric ?

[N5756v]

I have heard of people using tape on the rubber to fix the hole . Mine was to far gone for that . If interested in that drop me a pm and I will tell you where that info came from .

I am interested on how your conversion to electric goes if you go that route .

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[Bob_Belville]

Mine are Precise Flight's manual version. I pull up a lever on the floor beside the JBar to deploy. I like that, for one thing, like the gear, I can feel any changes in the linkage operation. I have no idea if the powered models can be converted.

[BobAustin]

Problem solved

Located a rep[acement "vacuum pot" and David at DuGosh installed it. 

Works great.  Took 4 hours to remove and replace.

[N5756v]

Did you happen maybe to find two "vacuum pots " or can you point me in the right direction?

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[BobAustin]

No such luck. Was expecting to wait a year or more...

[N5756v]

Bummer . It was worth a try

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[Jerry Pressley]

i have a pot for speed brakes if anyone needs

 

[SantosDumont]

My left electric speed brake failed after being installed for 20 years.  What a piece of garbage!

It was a $1k bill from Precise flight to refurb.  Now the only problem is that it fully extends a fraction of a second before the right one.

[gacoon]

At my annual last week the cables on my vacuum speedbrakes were determined to be unairworthy, even though they still worked.  I have an Aspen PFD and I am going to replace the vacuum AI with electric.  Out comes 1) speedbrakes, 2) vacuum system, and 3) standby vacuum system.  I’ll gain almost 30 pounds useful load and eliminate a bunch of maintenance items.

This is my second J model, have over 1000 hours in first one without the speedbrakes. Dont see the need for them with proper planning or negotiation with ATC.  Maybe if I was a turbo operating in the teens it might come in handy.  

Edited April 10, 2018 by gacoon

[kortopates]

8 minutes ago, gacoon said:

At my annual last week the cables on my vacuum speedbrakes were determined to be unairworthy, even tough thry still worked.  I have an Aspen PFD and I am going to replace the vacuum AI with electric.  Out comes 1) speedbrakes, 2) vacuum system, and 3) standby vacuum system.  I’ll gain almost 30 pounds useful load and eliminate a bunch of maintenance items.

This is my second J model, have over 1000 hours in first one without the speedbrakes. Dont see the need for them with proper planning or negotiation with ATC.  Maybe if I was a turbo operating in the teens it might come in handy.  

I understand, I don't use my speed brakes much at all, but they are nice once in awhile when I can't get what I want from ATC.

But its sure a lot easier to replace the conduit and the cables for the speed brakes than to deal with the wing holes you'll have pulling the speed brake cartridges.  In fact I can't imagine a pretty solution but then I have never seen that done. I can't be very sure, but I recall replacement cable conduit from Precise flight was in the $100-$200 range. I kept my engine driven vacuum pump solely for my spreed brakes, but that doesn't way much either.  

[gacoon]

On 4/9/2018 at 10:03 PM, kortopates said:

 I can't be very sure, but I recall replacement cable conduit from Precise flight was in the $100-$200 range. I kept my engine driven vacuum pump solely for my spreed brakes, but that doesn't way much either.  

That was a very good guess - I did email Precise Flight and cables are $100 and conduits are $80, that is per side.  I'm still inclined to remove them as I would get a very good weight payoff.  This is right out of the POH:

Speedbrakes 12.5 lbs, Standby Vac 12.04 lbs, Vacuum System 8.3 lbs.  Looking at gaining 32lbs useful load.  Digital AI is lighter also, but you really do not save any weight as the standby battery brings it back to about the same as the original AI.

Note: when I emailed Precise Flight they were nice enough to send me the old Mooney Vacuum speedbrake install manual, nice to know we can still get access to that.

 

 

Edited April 11, 2018 by gacoon

[carusoam]

PF does a nice job of manuals on their site...

Best regards,

-a-

[Precisemike]

Good evening,

Once in a while I view Mooneyspace and just read the threads mostly about speedbrakes ......I was the founder of Precise Flight along with W. D. Thompson and Later partner F. P. Thomas (both passed away).

 

I did most of the original speedbrake concept development and certification testing as well as experimental flight tests also.

I sold my share of Precise Flight years ago, but once in a while I look into the general aviation fleets to just see how some of my old projects have aged.

At the start of the speedbrake retrofit concept it was really tough sledding for a long time .........it was a lot of effort for little reward. Adding a whole new aero-control system to an existing aircraft was not a task for a sane person so being somewhat insane I had the gift needed to plod through a process that the FAA had zero protocol to guide them.

 

Over the years I have come to fly less and less and feel fine letting the young folks enjoy flying safe as that was the main goal of the speedbrake concepts.

 

While I know much of the early Precise Flight history, please do not try to obtain any current information on Precise products from me. Please contact Precise Flight directly.

 

Enjoy your Mooney's ......I enjoyed a lot of them.

 

Cheers,

Mike McDaniel

 

 

 

 

 

 

[carusoam]

Well then... Good morning! And Welcome aboard, PreciseMike!

great to make your acquaintance.

I have a pair of electrically activated Speed brakes on my Ovation...

Around here... we have three varieties...

• Mechanically actuated
• vacuum actuated
• electric actuated

I was most impressed during transition training... how fast an E-descent is with the PreciseFlight speed brakes deployed.

What’s your background? Aero? Mechanical? Machinist? Inventor? Pilot?

Thanks for stopping in. Stop back and see if any other questions arise... we have a bunch of enthusiast that love to discuss stuff like this...

Best regards,

-a-

[Precisemike]

6 hours ago, carusoam said:

Well then... Good morning! And Welcome aboard, PreciseMike!

great to make your acquaintance.

I have a pair of electrically activated Speed brakes on my Ovation...

Around here... we have three varieties...

• Mechanically actuated
• vacuum actuated
• electric actuated

I was most impressed during transition training... how fast an E-descent is with the PreciseFlight speed brakes deployed.

What’s your background? Aero? Mechanical? Machinist? Inventor? Pilot?

Thanks for stopping in. Stop back and see if any other questions arise... we have a bunch of enthusiast that love to discuss stuff like this...

Best regards,

-a-

Good morning,,

Not much to say about my life so far except have been fortunate to meet some nice people and not have too much time with the less nice folks.

As far as aviation ......at a early age I wanted to fly so I went to work at a carburetor rebuild factory where on a given night after high school classes I would tear down and chemical-dip clean a few hundred carbs.....later taking engineering and machinist classes I saved enough money ($450) to buy a TG-3A WWII training glider and it was a hoot to learn to fly sorta.......it was HEAVY and ponderous and later in life it was a great trainer for a flying Old airliner with failed hydraulics.

It took a couple years of savings but I finally bought a powered aircraft.....sorta.....a 1947 Stinson with a runout Franklin that I nursed along gently until it finally was just too tired to fly.....it was a easy airplane to fly but having a tail wheel the only instructor I could find was a WWII grumpy duster pilot that gave me 42 minutes of......."grouchy-instruction" and then he soloed me saying...."kid you seem inclined to kill yourself in this old wreck of a Stinson so I am just let you wreck without me".

i would guess that he was close to right about my flying but so far I have yet to wreck a aircraft and have a bit over 13,00o hrs and some a couple of lines added to my pilots license.  

I did a fair amount of experimental test flying in a lot of normal and some insane not normal flying things and with all the skill AND luck somehow have survived. 

There was a time in my past I thought I was a pretty red hot pilot with a few ratings but looking back at some pretty famous pilots I have flown with I come to know that I was likely a just a fair pilot most days and better than I really was for a few minutes when the chips were down.

i have been involved in a lot of aviation projects some worked out ok others were ........learning a learning experience to put it mildly.

i have taken a lot of risks flying and some were not well considered and that maybe ok on a personal level but it is not ok to let other folks follow a dangerous path just because I got lucky.

i have a great son inlaw and a couple years ago he informed me that he wanted to get his pilots license. They live in Seattle. He ask me if I would help him get started flying.........I told him that Seattle is not a great location for a VFR private pilot and even a inst. rating would not be good without the time and money to stay current. 

He had the flying bug bad so...........I found him a insanely expensive school to attend that would take forever to solo.  This may seem mean but I really don't want to watch them at risk simply my flying life experiences make flying look easy and safe......it is not.

Eventually aviation started to become a job and at times like having to pick through wrecks and funerals and court hearings the aircraft game started to lose its luster.

Obviously I have descended into a bit of a geezer ramble here so enough is enough.

If I have a wish for you Mooney folks it would be.........be safe and enjoy your aircraft.......for the most part I did.

 

Fly sane and safe.....