The Search Goes On

[busav8or]

In my continuing quest for the "perfect 170" I have visited with a 1954 B model with a beautiful new paint job and interior. Low time airframe (approx. 1600 hrs) and a low time SMOH (approx. 350). The only drawbacks which I can possibly see at this time are a rather limited, VFR only, panel and a generator instead of an alternator. I know several of you have probably replaced your generators with an alternator, and I was wondering what the cost might run. The "VFR only" panel includes a Garmin 250XL GPS/Comm and a Cessna transponder with an altitude encoder. What do you think would be involved on bringing this aircraft up to at least "light IFR" capability? Again, as before, thanks in advance for all the great advice I know I will receive!

[blueldr]

When it concerns the instrument panel, I'm at a loss to diffentiate between "light IFR" and any other kind of IFR. If you're flying solely by refence to the instruments, what is the difference? Only an idiot would attenpt to take an airplane like a C-170 into the type of weather that air carriers contend with on an every day basis, but they all need the same basic instruments to do the job.

[hilltop170]

Nowdays, my minimum IFR nav equipment is a 430W with a 396 back-up. I'm old enough now that I don't want to do calculations in my head anymore. The 396 has basic instrument backup if the whole panel goes T.U.

Standard IFR instruments are good enough but mix power sources for artificial horizon and turn coordinator, ie, vac horizon/electric coordinator in case one system fails. Get a fuel flow computer and calibrate it so you know exactly how much fuel you have.

Forget NDB approaches, they're dropping like flies. Shoot VOR approaches only if you absolutely have to. WAAS is so much more precise than ILS I don't even want to shoot another ILS.

Never push minimums in these airplanes. File IFR only if you're flying into stable or improving conditions. Never fly into ice, thunderstorms, or fog.

[busav8or]

Wow, I didn't mean to imply that I would be shooting Cat III ILS approaches to 600 RVR landings! I do THAT for a living! All I'm looking for is advice on what most people would consider enough instrumentation to safely climb on top of a cloud deck with 3000' tops for instance, or descend through a 1000' base layer. No ice, no thunderstorms!

[busav8or]

Thanks for your reply, hilltop170. You mention that your 396 has basic instrument back up. Is that the unit installed in your panel or the one mounted on the side (I'm looking at the pics you sent in response to my other post)? What do you use for Comm and backup Comm? Your panel layout would be my ideal!

[Bruce Fenstermacher]

I have two nav/coms, one with a glide slope. I also have an IFR Garmin 155 which does not have a map display. For a map display I currently have my Garmin Pilot III handheld wired into the 155 so it mimics and displays anything input into the 155. Total cost to me 10 years ago was $4000 ten years ago. I installed it all myself for $0 with the help of qualified friends.

I also have a 25 amp generator and a single stock venturi. I would fly light IFR with this setup under certain circumstances. In my case the single venturi pulls barely enough vacuum to operate my horizon and compass. I've always intended to upgrade to at least the dual venturi set up or more likely a super venturi to rectify this. I would not convert to a vacuum pump unless that opportunity feel in my lap for free.

First I can't see why the generator bothers you. It has never been a limiting factor for any type of flying I've wanted to do in my 170. It wouldn't even be part of my IFR go/no go thinking.

You didn't mention if the plane had a VOR receiver so I would assume it doesn't. And I'll assume it only has the one radio in the 250XL. This being the case I'd look for a King KX 155 probably with a glide slope. I'd also have to look at the Garmin SL30 which is slightly smaller than the KX 155 and would be new or newer. The SL30 would also integrate with some other Garmin products for such nifty things as automatic frequency swapping. If I didn't have an intercom then I'd be looking at the Garmin SL40 which is a SL30 with an intercom.

This would bring your equipment up to a VOR/LOC/GLS, two coms and a VFR only GPS for reference. There you go. That is all you need in my mind for the type of light IFR I would do in a 170. Of course we are assuming your basic AH and DG are operating satisfactorily on the vacuum system.

To improve you setup a pinch more and added probably the best bang for your buck I'd add a Garmin handheld capable of XM weather. This would be a 396, 496, 696 or one of the new 500 series. The x96s will be dropping drastically in price as the 500 series come on the market. Not sure of the 500 series but the x96 series can be wired to your 250XL. This wouldn't make either GPS IFR but a x96 with weather with give you the great weather situational awareness so you can avoid the IFR weather all together or stay in that "light" IFR. The x96 will also give you a pseudo backup system should your other instruments and avionics fail.

Next I'd upgrade your 250XL to a 300XL and have the installation certified for IFR use. I'd go with the 300XL as I believe that it will slide right into the present 250XL tray and I believe it the cheapest way to get IFR GPS since you already would have the 250XL.

If I really had lots of money say in the $10,000 range I'd replace the 250XL with a Garmin 430 which, besides getting a Garmin 530, is the cats meow.

Here are some thoughts I have on pricing.
King-KX-155 w/gls is in the $3000 range. Lots of good used units might save $$$
Garmin SL30 is in the $3700 range. Might be a used unit available.
Garmin 300XL is in the $3200 range, Probably used units available.
Garmin 430W is in the $8000 range. Used plain 430 units are becoming available as people upgrade to the W version.

All of the units need some kind of indicator. A new Garmin MD200-306 CDI is about $1800 but a King KI-208/209 can work for a quarter of that price. You will also in most IFR GPS installations need some kind of annunciator/selector system to switch what unit is driving an indicator if they are shared for example. These can run another $2000.

Add to the equipment cost the cost of the actual installation which could be another $1000 to $2000 depending on what needs to be accomplished.

One of the things that bothers me the most about IFR navigating using GPS is the ongoing cost of the database. Wouldn't be much of an issue if I was making 10 approaches a month with the GPS but to be ready all year long to do a few say 3 or 4 a year drives the cost of the approach to $100 or more a shot just to pay for the updates (forget the installation). This is why unless there is a specific need like only an GPS approach is available where you need to go, I would stick with VOR/LOC/GLS approaches with a VFR GPS to back them up and for situational awareness. GPS approaches don't buy you much unless you are talking WAAS approaches. If you need to fly a WAAS approach to the lower minimums your not in "light" IFR.

[busav8or]

Thanks, Bruce, for your detailed reply. I'm not bothered by the generator, but was more wondering why a lot of the planes I see for sale have upgraded to an alternator. I wondered if that indicated some problem with the generator setup itself. The aircraft I looked at does not have a VOR/LOC receiver installed and I do think I would like to have one; old school thinking I guess! It does have a double venturi system and the owner said it provides around 8 inches of vacuum.

[jrenwick]

I'll second what Richard said about the 430W/396 combination. A few years ago my 170 had a lot of older avionics: an ADF that had died, a KX125 NAV/COM, an Apollo COM, an ancient Trimble VFR-only GPS. At a minimum, I wanted an IFR-capable GPS. I consulted with my local avionics shop, and the cheapest setup that made any sense was to remove the ADF and replace the Apollo COM and Trimble GPS with a Garmin 430W. I added a Garmin 496 and hooked it up to the avionics bus for power. The power cable also carries data, so it automatically displays the flight plan or approach that's programmed into the 430. The handheld, with all of its additional capabilities, makes a terrific supplement to the 430.

By the way, all the new 430s now have WAAS capability. You get an active "glide slope" needle on any GPS approach, although you may have to remember your crossing minimums, and make sure it doesn't take you below them -- because the vertical guidance you get might be to some point other than the TDZ. (Edited) -- and because it uses GPS-derived altitude, which may be different from what's shown on a pressure altimeter.

The backup instrument capability Richard is talking about is the simulated instrument display on the 396 or 496. It gives you groundspeed, altitude, heading and such, in a format that looks like a standard instrument panel, more or less. Pilots have been able to demonstrate that you can fly by reference to that alone, and do a pretty good job.

[busav8or]

Thanks, John. Great info!

[hilltop170]

Thanks for your reply, hilltop170. You mention that your 396 has basic instrument back up. Is that the unit installed in your panel or the one mounted on the side (I'm looking at the pics you sent in response to my other post)? What do you use for Comm and backup Comm? Your panel layout would be my ideal!

Thanks for the compliment, that panel layout works very well in IFR. It was first configured that way in 1979 when the first radio upgrade went in with King radios. I saw no reason to change the alignment of instruments when the latest upgrade was done. The fuel flow computer really does lower the anxiety level on long flights when you're using fuel down to reserves.

Like you're suggesting, I only fly IFR when the conditions are favorable, no more minimums for me. The plane will do it but I'm just not interested in adrenaline rushes any more.

The 396 is the side-mounted portable GPS. It has a page with a basic instrument panel. It can be used in an emergency as the sole reference to fly the plane to an airport and make a pattern to land. I did it on a 150 mile trip with an FAA examiner and his comment was "if I hadn't seen it myself I wouldn't believe it".

The 430W is a nav-com and I also have an Icom A200 com-only. There is also an antenna jack for a handheld com.

[Bruce Fenstermacher]

Remember how old these airplanes are. Back in their early days avionics and incandescent bulbs drew a lot of power. Most of the 170s probably came with a 12 or 25 amp generator. The largest was 35 amps. As alternators became available, besides being the newest thing on the block, they could generate more power. An added bonus is you got that power right at idle not 1800rpm or higher.

Today this isn't as much a problem as avionics use a fraction of the amperage they once did. And we are starting to see fancy LEDs replace the incandescent lighting helping even more.

If this airplane's venturis can generate 8 inches of vacuum they aren't stock. At least one of them is a larger super venturi. Standard venturis are designed to pull 4 inches of vacuum. Doubling them doubles the volume not the pressure though you might see a slight increase. Modern gyros want about between 4.5 and 5.5 inches of vacuum. Mine are barely running on the 4 inches provided by the one stock venturi I have. The older AN gyros which were stock in our 170s only required 3.5 inches of vacuum.

Certainly 170s have been equipped with lot of nice stuff making IFR easier. A few of them even have simple autopilots. I take it from your login that you probably fly an Airbus. And no disrespect intended but you watch it fly itself. Till recently I watched the S-76 I fly, fly itself. We are talking about hand flying a single engine airplane with little airspeed or fuel to get around or over weather and to an alternate if necessary. You need to have a heart to heart with yourself and decide what you might actually need for the type of IFR you might attempt in a 170.

[n2582d]

Great discussion. I'm hoping to install a 430W in my 170. By the time I'm done with the rebuild they'll cost around $100. One thing that has been neglected in this conversation has been the transponder and encoder. I was planning on installing a Garmin GTX320 but after reading this article by the late Tom Rogers I'm not so sure anymore. I was thinking the digital Garmin would be more reliable than a King with the cavity tube. The price to replace a cavity tube on the ubiquitous KT-76A is around $800-900. Any thoughts?

[busav8or]

Thanks again, Bruce. I'm just going by what the owner told me about the venturis. I'm not looking at real serious IFR in a 170. I'd just like the ability to get "on top" and maybe back down through a 1000' to 1500' cloud deck; just enough IFR to add some flexibility to x-country legs. I guess the generator/alternator isn't really a concern after getting your opinion on the subject. As I said, I've seen several conversions and just figured a lot of these airplanes were converted for a reason. As far as the Airbus goes, you're exactly right on being an observer for the real serious IFR! I figure someday my company will go to the one pilot/ one dog cockpit as soon as they can get away with it (and they'll probably pay the dog more than the pilot)!

[GAHorn]

I view Bruce's comments as spectacularly good ones. I also like Richard's set-up. (not disagreeing with any of the comments in this thread).

Just as a "guide" to possibilities...not particularly recommended, I thought I'd tell about a friend of a friend who has a 170-B with old-style AN gyros (require only 3.5" Hg), standard dual venturis and a 35-Amp generator. He flys "light IFR" (occasional "vector" to climb to vfr, etc., non-precision appchs and usually only in the clouds long enough to climb to vfr on top or descend to vfr, or to use the occasional non-prec-appch as a "let-down" procedure). His only equipment is a single Narco 810 comm (he carries a handheld portable for comm backup), a KLN-88 Loran (originally designed/certified for NP appch's but now-days reduced to enroute/terminal IFR only), a Narco AT-150 txdr and Narco encoder, and a Garmin GPS-196 portable mounted above the panel (a la HUD) powered by the aircraft avionics buss (which allows it to revert to it's own internal batteries in case of complete elect-failure. Note: The Garmin portables all have ALL the Instrument approaches loaded in their databases, a very handy function, especially when "monitoring" a VOR or LOC appch. They are even WAAS-enabled and generate psuedo-GlideSlopes. SIDS/STARS can be individually def'd simply by entering the WP's into the flight plan. The Garmin 196 is the most bang for the buck, if you don't intend to subscribe to WX broadcasts (and my friend doesn't fly in WX so filthy that such service is necessary. (Who in their right-mind would deliberately launch single-engine into lines of TRWS or embededd-stuff at night?) Nor does he fly in widespread WX with ceilings/viz so low that an engine failure would likely put him into a deadstick to zero/zero....in other words,...NP appch minimums with cruising above an undercast is not too bad for single-engine, simple-panel flying. In fact it is very enjoyable.)
The Garmin portables also all have a back-up "partial panel" display that is quite reassuring in the case of gyro failures.
The standard dual venturi setup will power old style AN vacuum AH/DG's..but if you have the "modern pictorial" 3-1/8" gyro's you'll be happier with dual "super" venturiis, which will replace the standard ones using the same foot-print. They'll make enough vacuum to use a portable vacuum carpet-cleaner while in-flight. (Seriously, they have even been used to power pneumatic autopilots. They are infinitely more reliable than engine or electrically-driven vacuum pumps.... if you are flying you have vacuum! If you have an elect T&B and/or Garmin portable you have even more backup.)

You used the words "upgrade" to describe a conversion to an alternator. I would not necessarily call it an "upgrade" because alternator systems have their own drawbacks, but if you really need lots of electrical power they are useful. The reason I believe so many owners converted in the past was due to one of two possible reasons:

1- because of their addition of high-demand systems. Modern avionics and lighting systems do not require that sort of elect pwr. I would not spend $1K or more for an alternator. I would rather spend it on other things, since the elect. pwr is no longer req'd and generators are so reliable and rugged.

2- because their maintenance technician did not understand generator/regulators and because they made money selling conversions that seem to merely require component-replacement maintenance practices rather than troubleshooting. (The most common generator failure was a simple process of re-polarizing, but fewer and fewer "technicians" seem to grasp the concept of using a paper-clip to short across two screw-terminals.)

3- Some folks go absolutely crazy-with-worry about a short-period battery discharge while taxying around or with engines near idle. Ironically, these are usually the same folks who believe batteries are for engine starting. Of course, a battery is actually a reserve-supply of stored power in case of complete electrically-generated power, a very rare occasion. The momentary discharge while taxying at night with the taxi-light operating is quickly re-charged during the takeoff/climb event. The possibility of discharge during descent is not high, as the engine is (or should be) kept above generator "coming on" speeds anyway. The period of time that generator systems do not exceed electrical-demand in flight are easily met by the battery without fear of serious battery-depletion. (I simply can't imagine the dollars that have been wasted on alternator conversions by worrying about a non-problem such as this.)

On the plus side of alternator conversion: They are lighter-weight for their relative power-output. And alternator failures are usually repaired quickly by the local parts-replacers found at most shops these days. Most complaints about occasional "alternator-whine" in the headsets are eventually met with a shrug, if not outright toleration.

Anyway... I'm suggesting that you can make your airplane as sophisticated as your pocket-book will allow... or you can keep it as simple as "light IFR" requires...which is very little indeed. You can make a lot of flights and a lot of appchs into a lot of airports with a portable GPS if you buy the right one,...(legality being an entirely different subject, of course.)

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[jrenwick]

In the 90s I owned a different '55 170B than the one I fly now, and I replaced its generator with a Jasco alternator conversion. I don't know what amperage the generator was, but I noticed that it could not keep the battery charged with the avionics operating and the landing/taxi lights on. I live and fly under a Class B airspace with at least 8 airports under it (besides MSP), and lots of lakes and rivers (think floatplanes), so there's a lot of traffic under the shelf. I like to have my lights on a lot, and I didn't think I could do that with the generator.

Regarding minimum equipment for IFR of any kind, being completely legal is at the top of my list of requirements. I don't want ever to be caught with my pants down.