# Mechanical Backups Instruments?

Discussion in 'Instruments / Avionics / Electrical System' started by ToddK, Mar 29, 2018.

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1. Mar 29, 2018

### ToddK

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Mechanical Backups?
Thinking about installing an MGL ASV-1 or a Kanardia combo. They both have Airspeed, Altitude, and Vertical speed all in one place with nice big(ish) numbers. Thinking about putting it right in the middle with a slip ball right below it. I will make sure to have plenty of battery power in the event of an engine out.

Anybody have opinions about the necessity of mechanical backup instruments?

2. Mar 29, 2018

### BJC

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VFR daylight? No backups.

IFR or night? Backups.

BJC

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3. Mar 29, 2018

### Turd Ferguson

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Whatcha building? For VFR, if the engine quits, working instruments are of not much help.

4. Mar 29, 2018

### ToddK

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Putting a Chinook Plus 2 back together. Since it does not have nav lights and will have a 582, night flying is not part of the equation.

5. Mar 30, 2018

### rdj

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My VFR panel plan is based around a nice big EFIS that does everything because I love the technology and, hey, it's my plane and I want it. My backup plan is small (2-1/4" or 1") mechanical instruments for the FAR 91.205 set: airspeed, altimeter, compass, tachometer, oil pressure, oil temperature, two fuel gauges (for each tank), a handheld radio, handheld GPS, sectional maps and a smartphone for calling ahead if I need to enter controlled airspace. The EFIS is not on my required equipment list so if it goes tilt it just doesn't matter.

Legally, my understanding is that for (U.S.) experimental aircraft no instruments are required at all for Day VFR (just the ELT and a transponder/ADS-B if entering controlled airspace). 91.205 is only applicable for certified aircraft, or IFR / Night VFR flying in experimentals by specific wording in the operating limitations.

My 'backup' instruments aren't so much for getting me out of a pickle as they are for allowing me to safely and conveniently continue a flight far from home if need be, sans EFIS. Sans electrical system even.

With a Day VFR experimental your 'backup' requirements are dictated primarily by what makes you comfortable for safe continuation of flight should the MGL fail. If the only flying I did was local day VFR my backup instrument would be a yaw string. Down=getting slower, back=going faster, left/right=more opposite pedal, upside-down=upside-down.

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6. Mar 30, 2018

### SvingenB2

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I have an all electric system. Nothing mechanical at all. My view on this is is not to think in terms of "backup", but in terms of reliability. There are two main reason why electrical gadgets should shut down:
1 Empty battery
2 Fried due to poor electric quality (voltage spikes from the alternator and other stuff)

So, fix those two, and things will be OK. I'm installing a Mascot isolated DC-DC converter. It will clean the electricity, feeding the finer stuff with nice even 12-13V DC. Then, on the isolated side, I'm installing a backup battery that will last for 2-3 h running the EFIS and engine instruments, maybe 1-2 h with everything "ON". Besides I always have my Sky Deamon with GPS on my phone/pad, so I can fly just fine without any instruments operating and still have altitude and an indication of speed.

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7. Mar 30, 2018

### Wayne

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I have steam gauge back ups for airspeed and altitude - everything else is in the EFIS. I'm sure I could fly the Zenith Cruzer with no instruments at all in the event of a failure but these two are the big hitters. This is a religion and politics discussion for sure since it is such a personal perspective.

8. Mar 30, 2018

### Turd Ferguson

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I'm with BJC, I would not install backup anything.

9. Mar 30, 2018

### Kyle Boatright

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I agree for VFR. A handheld GPS will give you approximate altitude to conclude your flight, and you should be able to land the thing using visual references.

10. Mar 30, 2018

### rick9mjn

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here another idea, instead of a backup airspeed , how about adding a AOA (angle of attack) via, self powered "via air pressure" AOA indicator, also remember just one wasp in your pitot tube, and your std airspeed does not work....i know it happen to me............... good day. ..../rick...... Quote of the day =opinions expressed here are available free and may be worth the money you paid for them

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11. Mar 30, 2018

### Victor Bravo

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IMHO it depends on the type of flying you will be doing as well. I believe the Chinook is not historically an aircraft that you fly in crowded/complex airspace, but these days that can change. If you are in Class C airspace frequently, then losing an altimeter can create a problem with a tower or traffic controller, or your ability to report your position to other aircraft.

So if you will be flying in places where you need a transponder or constant communications with ATC, then you probably need a backup for altitude position reporting. If you need to stay above or below a certain altitude to keep clear of someone else's airspace for regulatory or safety reasons, then you can justify a backup altimeter.

I have no experience at all with the Chinook, but it seems to me that you should easily be able to fly it on "seat of the pants" feel in terms of a safe takeoff/landing in the event of an airspeed indicator failure (electrical or mechanical).

12. Mar 30, 2018

### dcstrng

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I’m not planning to run the contemporary glass-panel, rather a couple MGL multi-series; the FL-2 and E1 (EMS) which has almost anything VFR, but I am planning to run a steam ASI (more for my geriatric eyes, easier to glance at and see, than for redundancy) as well as a mechanical oil-pressure. – Nav will probably be my 72H Garmin, unless I win some low-level lottery…

13. Mar 30, 2018

### cluttonfred

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One model of the simple Hall wind speed indicator is good up to 80 mph which should cover your level cruise speed down to stall in a Chinook 2 and will get you a bulletproof mechanical backup ASI for about $40 including the bracket and shipping. Otherwise, I would second the suggestion a differential pressure angle-of-attack or "lift reserve" indicator rather than an ASI as your backup as it seems pretty much perfect for old eyes and simple flying. See this link and the attached article. I especially like this style with the wing profile and sideways mounting to make it very intuitive. #### Attached Files: • ###### My POV of a DIY AOA-LRI Indicator (FWIW, YMMV, LOL) _ EAA.pdf File size: 1.9 MB Views: 15 Daleandee and MadRocketScientist like this. 14. Mar 31, 2018 ### Daleandee ### Daleandee #### Well-Known Member Joined: Sep 11, 2015 Messages: 895 Likes Received: 561 Location: SC Anyone that knows me knows that I really like my LRI unit and highly recommend them. Do you need one? You shouldn't ... but having one can be a plus. I installed mine initially as a backup to my ASI but found it to be good information to have available. The ASI gets little use these days as I like the LRI for take-off and landings. If I use the same readings on the ASI on approach, regardless of weight, temperature, density altitude, etc. I seem to make consistently better landings. No ... I don't need it but it sure is nice to have! Dale Williams N319WF @ 6J2 Myunn - "daughter of Cleanex" 120 HP - 3.0 Corvair Tail Wheel - Center Stick Signature Finish 2200 Paint Job 171.9 hours / Status - Flying Member # 109 - Florida Sonex Association Latest video: https://www.youtube.com/watch?v=1VP7UYEqQ-g Last edited: Mar 31, 2018 15. Mar 31, 2018 ### ToddK ### ToddK #### Well-Known Member Joined: Jan 13, 2016 Messages: 176 Likes Received: 56 Location: Humble I am totally sold on the lift reserve indicator. I looked into it last night and immediately saw its value. Since the Chinook is a pusher, would it be a problem to install this thing on the nose, provided I Make sure the angle is correct in relation to the wing? 16. Mar 31, 2018 ### Daleandee ### Daleandee #### Well-Known Member Joined: Sep 11, 2015 Messages: 895 Likes Received: 561 Location: SC First some housekeeping ... in my earlier post I wrote "If I use the same readings on the ASI on approach, regardless of weight, temperature, density altitude, etc. I seem to make consistently better landings" but I meant to write ... If I use the same readings on the LRI on approach, regardless of weight, temperature, density altitude, etc. I seem to make consistently better landings. * * * * * To your question ... I believe that as long as the probe gets clean air (not interrupted by prop wash or other structural parts) that it will work as advertised. The angle to set the probe at will be determined by flight testing at altitude. The version you purchase may have specific instructions so I won't go into that here. Chuck Yeager said "if you don't know your angle of attack you shouldn't be flying the plane" in reference to seeing an AOA gauge on a panel. Chuck is the man alright ... I ain't so I'm keeping mine. If Chuck ever comes to fly mine I'll remove my LRI so he won't have to look at it. 8~) If you go to full screen and high HD mode you can read my LRI during an approach when it was a little bumpy. Notice how steady the readings are: https://youtu.be/0afcagd70UE?t=530 Here you can get a really good look at the LRI on final approach. This was taken years ago during flight testing. https://www.youtube.com/watch?v=WjA7JDJVKeQ Dale Williams N319WF @ 6J2 Myunn - "daughter of Cleanex" 120 HP - 3.0 Corvair Tail Wheel - Center Stick Signature Finish 2200 Paint Job 171.9 hours / Status - Flying Member # 109 - Florida Sonex Association Latest video: https://www.youtube.com/watch?v=1VP7UYEqQ-g gtae07 and ToddK like this. 17. Mar 31, 2018 ### ToddK ### ToddK #### Well-Known Member Joined: Jan 13, 2016 Messages: 176 Likes Received: 56 Location: Humble Just heard back from a guy who makes one of these, he sent me a pic from a Challenger nose installation. 18. Mar 31, 2018 ### cluttonfred ### cluttonfred #### Well-Known Member Joined: Feb 13, 2010 Messages: 6,365 Likes Received: 2,231 Location: World traveler Check out the link and attachment that I posted, these things are not hard to make and the DIY version is less than$100 all in. The Dwyer Minihelic mechanical differential gauge itself is under \$50 and the probe can be easily made from a couple of pieces of hard plastic (Nylon, Delrin, etc.), a couple of aluminum tubes, and some plastic tubing. After that, it's a question of how fancy you want to get (adding the wing-profile to the pointer, custom printing a decal for the face, etc. or just use the as is and add some colored tape). The calibration process is the same whether it's store-bought or homemade.

19. Apr 15, 2018

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Any ex-Military that I know that flies small aircraft, especially homebuilts, always fits an AoA or LRI and swears by them.

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20. Apr 16, 2018

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