THE DESIGNEE CORNER

INSTRUMENTATION FOR THE VFR HOMEBUILT

By Antoni (Tony) Bingelis EAA Designee Co-Chairman

8509 Greenflint Lane Austin, Texas 78759

ON, JE THING CAN be said about the instrument panels in homebuilts. They are frequently quite different from the usual run-of-the-mill installations. A few are so different that only the builder knows where to look to find his readings. One reason for this unique display of individuality

can be traced to the typical nature of the builder. Building an airplane

takes a long time, in whatever relative terms you want to measure time. During this period the builder is continuously on the hunt for materials

and equipment for his project. He acquires all sorts of wonderful gadgets and goodies that he could use . . . will use. The time arrives for developing the instrument panel layout and suddenly he realizes that he has more instruments than he really needs. He hates to discard anything and often installs

several extra instruments merely because he has them. For one thing an instrument panel that is "loaded" does look impressive, doesn't it? So,

why not? If the extra weight is not critical and you have the space, you might find it quite pleasureable to

give in to your own special need to be just a bit different. It is a lot better to relieve this impulse to be different and experiment with different panel instrumentations than it is to change any of the structure that the designer has carefully worked out

and proof tested to assure a safe airplane. If you are not particularly interested in cluttering an instrument panel with goodies, you can simply install the m i n i m u m of instruments necessary to get your little sport plane airborne . . . legally. You know, I'm sure,

that there is a m i n i m u m of instrumentation that is acceptable by the FAA. When an aircraft is first granted its airworthiness certificate, the FAA inspector issues a document known as the Operating Limitations. This document details exactly what that airplane will be permitted to do, where, when and how. This paper also states whether the airplane is to be operated in other than VFR,

DAY ONLY flight conditions. It is likewise possible to obtain certification for VFR DAY or NIGHT, or IFR.

Regardless of your preference for the type of operating limitations you want approved, the type of flight conditions your aircraft will be permitted to operate under will, essentially, be determined by the type of instrumentation and equipment installed.

Of course, the inspector also has to be convinced that the aircraft is capable of performing under the conditions

designated. In other words the FAA stipulates what instrumentation and equipment is necessary for your aircraft under different flight conditions. Just installing a bunch of instruments will not automatically qualify your aircraft for IFR ... or VFR Night Operations . . . or even plain old VFR, Day Only, if you don't have the right instruments and equipment. FAR Part 91 only speaks of the instrumentation required of standard category aircraft and is silent on

the subject of amateur built aircraft. Nevertheless, Advisory Circular AC 20-27A suggests that your amateur built aircraft be equipped in conformance with the applicable paragraphs of FAR Part 91, Section 91.33 as follows:

Incidentally, the FAA inspector usually lists the above instruments as necessary for VFR operations so, in effect, FAR Part 91.33 does apply

to the homebuilt, too.

THE AIRSPEED INDICATOR

This ordinarily, is a store-bought instrument weighing somewhat less than one pound and fits a 3'/«" hole in the instrument panel. It can be obtained to read in k i l o m e t e r s per hour, miles per hour, knots, or a combination of mph and Kts. For

that matter, you can even make your own airspeed device and calibrate it in yards per hour if you want. The

rule requirement is for an airspeed indicator. Most builders are q u i t e

content with the usual store-bought gauges. C e r t a i n l y an airspeed indicator

should be capable of indicating the m a x i m u m d i v i n g speed which the

aircraft is capable of reaching safely. However, I think it should also be obvious that an airspeed indicator that reads 0 to 140 mph is more appropriate for a slow sport plane than one that reads 0 to 700 mph. Sensitivity in the lower speed range of

the scale is more important than a conversation piece.

VFR DAY ONLY (This is the minimum instrumentation for any aircraft.!

AIRSPEED INDICATOR ALTIMETER MAGNETIC DIRECTION INDICATOR (Compass! TACHOMETER (For each engine) OIL PRESSURE GAUGE (For each engine using an oil pressure system. I OIL TEMPERATURE GAUGE (For each air-cooled engine.)

TEMPERATURE GAUGE (For each liquid cooled engine.)

FUEL GAUGE INDICATING THE QUANTITY OF FUEL IN EACH TANK LANDING GEAR POSITION INDICATOR (For retractables.)

THE ALTIMETER

The regular a l t i m e t e r also fits

into a 3'/K" hole. It is usually calibrated to read in feet. For our purpose altimeters are divided into two basic kinds, the sensitive altimeter and the non-sensitive type. Take the sensitive type if you can get it. Not because it is more expensive but because it is far better suited to the light plane. A sensitive altimeter will register even a modest change in altitude while the non-sensitive altimeter will not even move its stubborn hands until you have gained or lost many, many feet of altitude. SPORT AVIATION 59

The stark simplicity of the minimum VFR panel is startling at first sight. Note visual fuel gauge, panel center.

THE MAGNETIC DIRECTION INDICATOR

A regular aircraft magnetic compass will take care of the requirement

for a magnetic direction indicator.

Homebuilders seem to prefer the

small Airpath Compass (C 2300 series) rather than the larger variety, including the WW II surplus stuff. Although I have seen automotive

and boat compasses installed in aircraft, I personally think that is poor economy, if indeed, they are cheaper

than serviceable aircraft units. Most FAA inspectors will not permit their use as the primary magnetic direction indicator.

A compass cannot be installed just

any place there happens to be space.

Finding a good location can present a

problem . . . especially since it must

be located where it can be seen and still be least affected by the magnetic influences of the aircraft's steel structure.

If you have a galvanized fuel tank

behind your panel, it will affect the

compass. If you happen to have a biplane, all of that tubing, cabane struts, and wires could generate enough magnetic activity to cause the compass to whirl and gyrate about like a tired belly dancer. Because of this, some builders are locating their compass in the top wing cut-out directly overhead as this is a good loca-

tion for biplanes. In other designs, it seems best to locate the compass on top of the instrument panel just behind the windshield. Perhaps the all-wood aircraft builder enjoys the easiest time of it when it comes to installing the compass in a magnetic free location. THE TACHOMETER

Consider installing a tachourmeter, or a "recording tach" as it is often called, rather than a plain tachometer. In addition to showing the en60 MARCH 1975

The minimum VFR panel.

gine revolutions per minute that you need to know, it also logs, automatically, the engine hours. The FAA approves of this method of logging engine hours, as without

a doubt it does much for the accuracy of maintenance and flight records. People do forget to log their flight time regularly and accurately, and as a result many an engine or aircraft is older than the records indicate. That advertised, "only 1245 hours since new" engine might really be closer to 2000 hours since new . . . how can you tell? Incidentally, be sure that you obtain the right kind of a tachourmeter for your engine. Some

are right hand rotation and others are counter-clockwise. So, always give the engine type and dash number when ordering the instrument. For example, a C-85-12F will take a different tach than will a C-85-8. PRESSURE AND TEMPERATURE GAUGES

These are usually of the automotive variety. The thing to remember if you are going to use automotive

type gauges is that they are slightly smaller than the standard small air-

craft gauges. The automotive gauge fits into a 2" hole in the panel . . . not a 2'/4" hole. THE FUEL GAUGE

Any type of fuel gauge will be suf-

ficient to satisfy the requirement if

it indicates the quantity of fuel in each tank. This means, of course,

that the time honored wire and cork

float gauge is acceptable. Fuel gauges vary more in style, design and installation than any other instrument found on aircraft. Whatever type you use, be sure it has a reasonable degree of reliability and accuracy. If you plan to use a clear plastic or glass tube in the cockpit which shows the level of fuel remaining, I would

suggest you first check with your FAA

inspector as he may not approve of such an arrangement in the cockpit area because of the possibility of fuel leakage. THE LANDING GEAR INDICATOR

Although it is hard to visualize an airplane sophisticated enough to have a retractable gear being matched up to minimum instrumentation, it is possible. So, in keeping with that concept, all that would be necessary is just a simple wire or indicator which would show the gear's position. OPTIONAL INSTRUMENTS

If you want a panel with a bit more utility than the bare minimum VFR instrument requirements consider adding a turn-slip (turn-bank) indicator. Of course, if you add a turnslip indicator you will have to install a venturi or a vacuum pump. High on my priority list of optional instruments are a cylinder head

temperature gauge, a 0 to 2000' vertical velocity indicator (rate of climb) and a "G" meter. The cylinder head temperature gauge, during the early testing stages helps reassure you that your cowling, baffles and cooling system are doing their job effectively. The rate of climb is a nice deluxe item and the "G" meter is very important during the testing period. NIGHT FLYING REQUIREMENTS

For VFR flight at night, the follow-

ing equipment must be added to the minimum VFR, DAY ONLY instruments and e q u i p m e n t previously listed: Approved position lights.

ANTI-COLLISION LIGHT SYSTEM

An adequate source of electrical energy for all installed electrical and radio equipment.

One spare set of fuses, or three spare fuses of each kind required.

Note: A landing light is not required except for aircraft used for hire. (Amateur aircraft, of course, cannot be used for that purpose.) FAA says nothing about cockpit lighting of the instruments yet, obviously, some provision must be made for that sort of thing. It should also be apparent that to be approved for night operations, virtually requires the installation of a complete

Nicely arranged panel on a Buecker Jungman. Note that the flight instruments are grouped for quick scanning.

electrical system to include a battery, generator and voltage regulator. Since you are going that far, why not include a starter too? The whole package will mean an additional 40-

60 pounds to the aircraft's weight. Would you fly at night often enough

A well equipped panel on a tiny single sealer. Efficient utilization of space.

to make it worth carrying all that

weight around permanently?

DESIGNEE NEWSLETTER SUBSCRIPTIONS

In addition to Tony Bingelis' monthly column, THE DESIGNEE CORNER, EAA Headquarters publishes a monthly Designee Newsletter containing even more "How To" material, a compendium of the previous month's Designee inspections and a summary of all homebuilt accidents occurring around the nation the previous 30 days. Any EAA member can subscribe to the Designee Newsletter for $7.00 per year. Make your check payable to:

Another single seater with a well equipped display of instruments for VFR flying. Note the completely unrelated grouping of the instruments among photos illustrated.

EAA P. 0. Box 229 Hales Corners, Wise.

53130

An aesthetically pleasing panel arrangement for a side-by-side installation. Such an arrangement would permit the grouping of flight instruments on the left and the engine and other instruments on the right.

COMPASS ALTIMETER

TACHOMETER

AIRSPEED

OIL OIL

tt

I

SWITCHES, ETC

PRESSURE TEMPERATURE

tt_

FLIGHT INFO

I

ENGINE INFO

BASIC VFR INSTRUMENTS

Individuality? Yes sir. Well equipped panel with a couple of options not

exercised yet. Slanting of the instruments left and right is puzzling. SPORT AVIATION 61