The International Cessna^® 170 Association

Does anyone know what the dimensions are for correct landing light bracket adjustments. There is an adjustment chart in my service manual that includes the 172 with the same type brackets but of course the 170 would be different. I would like to see what the landing and taxi light look like when properly adjusted, instead of using the eyeball method.

The landing/taxi lites can be viewed from the front of the wing, looking aft. There are 8 screws (4 on each bulb) that are given the following nomenclature:
Inboard bulb: Upper Left (Inboard) screw = #1. Upper Right (OUtboard) screw = #2. LOwer Left (Inboard) screw = #3. Lower Right (Outboard) screw = #4.

OUtboard bulb:Upper Left (Inboard) screw = #5. Upper Right (OUtboard) screw = #6. LOwer Left (Inboard) screw = #7. Lower Right (Outboard) screw = #8.

The adjustment dimensions are from the surface face of the mounting plate forward of spar, (PN 0523106, IPC pg 9, Fig 4, item 25 onboth A and B models.) From the surface of that mounting plate to the rear of the bulb holder (channel PN 0523117, Fig 89 B-models, Fig 65 A models, item 5, which holds the bulb by it's lip, the following dimensions apply:

Screw 1 .56"
Screw 2 .62"
Screw 3 .62"
Screw 4 .68"
Screw 5 .56"
Screw 6 .90"
Screw 7 .50"
Screw 8 .84"

Note: The above dimensions are identical for both 170 A/B and 180 aircraft.

Just for fun,I think I'll complicate the issue. I assume that these measurements at the light assembly are for a stock 170 A or B. I further assume that these measurements will result in the landing/taxi lights shining at a particular angle or at a particular place in front of a standard unmodified 170A or B.
.Now,what if the airplane in question is no longer fitted with a Scott 3-24B (2000) tailwheel asembly as per the TCDS,but has been modified with a Scott 3200 as most of them have been? What if it has 180 gear legs? What if it has 700 or 800 tires,or (gasp!) even the dreaded 850's? What if it has the hallowed L-19 tailspring? Any of these mods,or any combination of them,would rsult in a change in the angle of attack in the 3-point position,therefore the specified adjuster measurements would not result in the lights shing where you want them.
Is there an alternative spec on where the light should shine?--for example,at 25 feet infront of the airplane the taxi light should be 4 feet from the ground. Remember,ya don't want to blind the on-coming traffic......

Eric

As a practical matter not enough difference to matter even on Gar aero 8,50x10s'

Ah, Just the information I needed.
thanks to all. Now I have that warm fuzzy feeling.

And keep in mind that no adjustment is going to result in "great" illumination of the runway you are to land on. It is better than none by a whole lot, but far, far, far from the illumination experienced by auto headlights, both old and new. Sure helps if the runway is lighted at ground level. Not bad for taxiing around once on the ground though.

Eric, ...there are those who would argue the C-170 specs do not apply to airplanes no longer C-170's.
For what it's worth, (and much to the amusement of Bruce (N3243A) I'm sure) ...my lites are adjusted to my own pleasure. My outboard (taxi) light is adjusted to a point on the ground 75' ahead and slightly right of center, while my landing lite is adjusted to a point 75' ahead of the aircraft, 5' above the ground and slightly left of center. This gives me the best taxi and landing illumination both on the ground and in flight.
The problem is that in flight the land lite needs to illuminate the touchdown area despite flap setting, yet be useful as a taxi lite in case the taxi lite fails. Conversely, the taxi lamp has to be at least marginally serviceable in the event the landing lamp fails.
I'm working on a "clip-on" diffuser lens for the taxi lamp to convert it from a spot-lamp to a better taxi lamp. I'll let ya'll know if/when I'm successful.

Unfortunately it takes more to amuse me than your personal light adjustments George, but I'll try to generate some humor anyway. Since the specs given by Cessna for landing light adjustments are advisory rather than regulatory, you can adjust your lights so they point anywhere you want. Or can you? Can a FSDO inspector write you up for lights that don't meet adjustment spec? After all, the airplane would no longer conform to manufacturer's specifications and thereby violate it's airworthiness. Do the FSDO guys carry calipers in the field to try to bust outlaws like you that just set 'em anyway they want?

By the way, will your "clip-on" diffuser lens for the taxi lamp be an "owner-produced" part? If not, on what basis are you going to install it? Are you going to get a Field Approval?

Just poking some fun here, Bruce, '53 170B

Allll-riiiiiiiiggghtyyy nooooowwww!! Bruce is getting it now!
At some point I guess tire pressures can be scrutinized, but the b--stard better be quick or he'll have skid marks on his fingers!
I actually intend to have an STC available for the lens.