What flight/engine instruments do we really need?

[Frank Giger]

This may sound pretty goofy, but the question comes from a series of conversations I've had with other pilots and builders, and the opinions vary widely.

Bear in mind I'm talking about strict VFR and no interaction with the ATC at all.

I've got in my little open cockpit Nieuport 11:

Altimeter
Air Speed Indicator
Compass
Turn and Bank (slip) Indicator
Tachometer
Oil Pressure Gauge
Oil Temperature Gauge
Fuel Gauge (sort of, it's like in a Champ, a stick on a bobber in the tank in front of the windscreen)

I put them all in because it's kind of expected for them to be there, but in honesty I only use three, and sometimes a fourth:

Slip indicator*
Oil Pressure
Oil Temperature
Compass

(I omitted the gas gauge as it's right in front of me bobbing around and pretty hard to miss)

I will look at the ASI or the Altimeter once in awhile, but since I'm a low and slow guy can tell you what they're indicating by the sing of the wires and how big the cows in the field are. I'll use the compass to plot the direct course back to the airfield if I'm not using landmarks.

The tach was useful in determining what it's turning at the start of flight testing, but now I can tell by sound and vibration. Again, it's a VW and isn't going to over speed with that big wooden prop in the front.

My ASI has been unreliable from the start, reading 10 MPH too fast. I'm going to pull it and test it, and have been given a lot of advice on where to move the static port to if it's okay. I'm not too hot to get it done, as I never really pay attention to it. My built-for-drag airplane isn't going to over speed, after all.

I mentioned either just omitting it or replacing it with a mechanical one that relies on some music wire and a paddle on a scale hooked to wing strut, only to be met with a look of dismay by a fellow pilot.

"You have to have an airspeed indicator," he insisted.

"Why?" I asked, and he shook his head and walked away, muttering, as if I was ignorant about something basic and true.

Your thoughts?

* With a free-flying rudder, the ball is actually the most important instrument on my panel. If the rudder is off to one side even just too much, one has a tendency to correct for the roll with the aileron in the opposite direction subconsciously. One can wind up pretty cross-controlled in level flight. The guys who fly this type of plane warned me about it, and damned if they weren't right - it's easy to do! So checking the ball regularly is something I do in flight.

[Marc Zeitlin]

This may sound pretty goofy, but the question comes from a series of conversations I've had with other pilots and builders, and the opinions vary widely.

There can be no "opinions" on this, as CFR 14 Part 91.205(b) is very clear as to what instruments are "needed" for day VFR flight. See:

http://rgl.faa.gov/Regulatory_and_Gu...tLookup/91.205

for the 10 instruments required. It's not that they're "expected" to be there - they're required by law.

Now, if you want to have MORE than these, you're certainly welcome to do so, but you have no choice about those 10. For your plane, you won't need the MP gauge or gear retract indicator, nor (probably) the coolant temperature sender. So you've got 7 required instruments for YOUR plane. They're not negotiable.

[Floatsflyer]

There can be no "opinions" on this, as CFR 14 Part 91.205(b) is very clear as to what instruments are "needed" for day VFR flight. See:

http://rgl.faa.gov/Regulatory_and_Gu...tLookup/91.205

for the 10 instruments required. It's not that they're "expected" to be there - they're required by law.

Now, if you want to have MORE than these, you're certainly welcome to do so, but you have no choice about those 10.

.

Uh, do you think the owners of J3 Cub and similar aircraft from the 30's and 40's who have 4 instruments might be surprised by this?

[rwanttaja]

Uh, do you think the owners of J3 Cub and similar aircraft from the 30's and 40's who have 4 instruments might be surprised by this?

Which one(s) do they lack? I presume you're referring to J3 panels other than this:

In this day-and-age, I feel little need for a compass. Airspeed gives me some reassurance, but I don't use it very much. Altimeter, where I'm based, is vital due to overhead Class B airspace.

Ron Wanttaja

[Bill Greenwood]

Just as the illustration by Ron shows, an original Piper J3 Cub has 6 panel instruments, that is 5 dials with the last one being a 2 in one. Reading from left to right, Tachometer, Airspeed indicator, Magnetic compass, Altimeter, and 2 in one with oil pressure on the top half and oil temp on the bottom half. So 6 instruments, plus one more, not really an instrument or gauge but the very important fuel quantity indicator which is a wire sticking up out of the fuel tank cap just in front of the windscreen. It has a cork float that floats on top of the fuel and is accurate in calm conditions. A Cub holds only 12 gal of fuel burns about 3 1/2 gph, Lots of people have butchered up cub panels so there are often non original ones, often a ball slip/skid is added under the compass and is handy. I sure would want a compass if I flew a plane very far.. Even a Jenny has a compass and they are cheap. Cubs have and do go cross country , just takes awhile or about 3 hours max range ( 2s better) for about 200 mile per leg.By the way if you have never flown a Cub do so as soon as you can, and get a real one not the modern replicas. Best early morning, or nice evening long as its calm, Did you know a Cub has the same wing area as a Mu2? The lowest number on the airspeed indicator is 40 mph and doing a stall with just a touch of power will be below the 40 about 38mph. And they spin and loop nicely just like a real airplane. If you cant get a real Cub a Champ is pretty good, but who needs to fly from the front seat? You can approach at 45 mph and land really short without reliying on brakes which are none too powerful. Tower once asked me to make short approach and with a headwind I landed on the numbers and also stopped on the numbers. Great first time trainer, head and shoulders over Cessnas. makes much better pilots.

[Dana]

There can be no "opinions" on this, as CFR 14 Part 91.205(b) is very clear as to what instruments are "needed" for day VFR flight. See:

http://rgl.faa.gov/Regulatory_and_Gu...tLookup/91.205

for the 10 instruments required. It's not that they're "expected" to be there - they're required by law.

91.205 only applies to aircraft with standard category airworthiness certificates, not experimentals.

[rwanttaja]

....I sure would want a compass if I flew a plane very far.. Even a Jenny has a compass and they are cheap. Cubs have and do go cross country , just takes awhile or about 3 hours max range ( 2s better) for about 200 mile per leg.

I'm afraid we're going to end up merging this thread with the "Old-Technology-No-One-Uses-Anymore-But-Young-Pilots-Still-Should, Dad-Gum-It" one. Navigation with map and compass is a laudable skill, but I'm not sure how relevant it is today.

Back when I was a young 'un, I took lessons in a CAP Citabria. It didn't have a DG (did have a turn and bank), so for the "Hood" portion of the flight test, I had to learn all the intricacies of the whiskey compass...leading when turning in one direction, lagging when turning the other, offsets when climbing or diving, etc. Must have worked, since I passed. Don't remember any of it, now, just how many times Dead Men Can Vote.

But even on cross-countries (in North Dakota), the compass actually rarely got a look. I'd align the course line on the chart with the aircraft, and turn until the section lines matched up with the lat/long lines. But I bet it's mostly ignored these days.

Today, in Western Washington state, I use three primary methods of navigation...none of which involve compasses.

1. IFR, as in "I Follow Roads". Big highways to most major destinations, and, more importantly, through passes in the mountains. If a 40-HP VW Bug can make it over the pass, so can a 65-HP Cub.

2. GPS. I bought a Garmin hiking GPS from REI. Cost $120, which is actually less than a new whiskey compass.

3. RNAV...which, in this case, means "Real-Time Navigation Around Volcanoes." They're all pretty distinctive in appearance, so they give a good bit of feedback as to position. Don't help that much flying away from home, but coming back from the North and West, all I have to do is point the nose at Mt. Rainier.

Ron Wanttaja

[Marc Zeitlin]

91.205 only applies to aircraft with standard category airworthiness certificates, not experimentals.

Ugghhh. A previous long response disappeared into the 7th dimension....

Suffice it to say that yes - you're correct. The OL's for EAB aircraft do not expressly require compliance with 91.205(b), and my bad for forgetting that point in response to the OP. I should have been softer in the response and used 91.205(b) as a reference, not a requirement.

To summarize my original response to THIS post, however, I'll argue that even if not legally required, it will be difficult to get a FSDO or DAR signoff without the (b) section instruments installed, and any ramp check of an aircraft without any of the (b) instruments would result in a 91.13 violation. IMO.

I would be interested to hear from anyone who's either attempted or succeeded in getting an AC from a FSDO or DAR with missing 91.205(b) instruments, and during the attempt, what the response was to pointing out that 8130.2<x> doesn't anywhere explicitly require 91.205(b) compliance.

Sorry for the dogmatism...

[Bill Greenwood]

There can be no "opinions" on this,

Ugghhh
In my opinion when someone writes that "there can be no "opinions" on this, it strikes me as unusually narrow minded, especially on a forum where other experiences , knowledge and yes opinions are part of the discussion. Its possible that the writer really is more knowledgeable than everyone else and that his opinion that no one else should have an opinion reflect the actual case,as if Neil Armstrong said what the moon feels like.However I dont recognize the name as the same as the most experienced pilots or designers or builders around. Can anyone help me if I am overlooking this?
. P S, Out of curiosity I looked up the specs on Cozy planes. Years ago a friend built one the first canard design fiberglass Rutan lookalike planes, cant recall for sure think it was a pusher. It would not get off the ground at our 8000 ft alt and he never flew it. The Cozy specs, as claimed are good, 1200 fpm climb, 185 mph cruise for 1k., Its looks are , in my opinion . different, like most Rutan similar designs

[Floatsflyer]

Ron's diagram of a Cub panel shows 5 instruments, 6 if you include the combo oil pressure and oil temp. The primer and the cabin heat are not instruments. Neither is a fuel gauge, either a float/wire thingy on the nose tank or a glass gauge positioned on the left side wing root on much later models. Even if you add a turn and bank ball to make 7, you still don't have the 10 Marc demands to be required.