Landing Light CB

f he had simply stated that the bulb drew thus and such a current and was
used
in a swing-down application, I would have simply stated that he was using the
wrong bulb number

Ok here are the facts.
The plane is a 1973 Cessna 172 M.
The landing light is a 4522. 250 watt at 14 volts. By ohms law is draws 17.86
amps.
The Circuit Breaker Part number is S-1360-20---20 amp
This is from the equipment table on page 20-35
Either the Cessna book is wrong or the light should be of lower wattage or the
circuit breaker should be of a higher amperage.
Hank

On 22 Aug 2004 23:13:09 GMT, (Hankal) wrote:

f he had simply stated that the bulb drew thus and such a current and was
used
in a swing-down application, I would have simply stated that he was using the
wrong bulb number

Ok here are the facts.
The plane is a 1973 Cessna 172 M.
The landing light is a 4522. 250 watt at 14 volts. By ohms law is draws 17.86
amps.
The Circuit Breaker Part number is S-1360-20---20 amp
This is from the equipment table on page 20-35
Either the Cessna book is wrong or the light should be of lower wattage or the
circuit breaker should be of a higher amperage.
Hank

Sounds just about right to me. Have you checked your grounds and for
a chafed wire yet? Or is the barking of the newsgroup dogs starting
to get to you?

A 4522 lamp is a PAR46 bulb, 13 volts 250 watts 290,000 cp
5.75 inch dia with a rated life of 25 hours. 250w/13v = 19.23 amps
If it runs at more than 13 volts it will draw more current and burn
out quicker.

A 20 amp breaker is running very close to its limit powering this
lamp. Since these breakers are thermal breakers a poor crimp or a
loose screw on the breaker terminals will cause extra heating and
cause the breaker to trip at lower than 20 amps. As these breakers age
they trip at lower than rated current due to oxide build up on the
internal contacts.

The next smaller wattage in the same lamp shell size, PAR 46, is a
4537. This is rated at 100 watts 13v, 200,000 cp

My 172M uses two 4905 lamps at 100 watts each which are PAR 36. These
are a smaller diameter lamp and will NOT fit in t PAR46 mount.

Look for hot crimps on the breaker wires and chafed wires going to the
lamp.

On 22 Aug 2004 21:59:44 GMT, (Hankal) wrote:

I suspect someone installed the wrong lamp in your aircraft. Many
14volt 172's use a par36, 4509 lamp which is rated at 13 volts, 100
watts, 7.7amps.

You need to look up in the parts list for the aircraft the correct
part number of the lamp.

I did look at the parts manual and it states GE 4522 and the breaker is a 20
amp.
Would a 4509 or 4905 fit in the same housing?
Hank

Sounds just about right to me. Have you checked your grounds and for
a chafed wire yet? Or is the barking of the newsgroup dogs starting
to get to you?

I have come to the conclusion to install a 100 watt

The next smaller wattage in the same lamp shell size, PAR 46, is a
4537. This is rated at 100 watts 13v, 200,000 cp

I will put one of those in mine

On 24 Aug 2004 00:24:21 GMT, (Hankal) wrote:

Sounds just about right to me. Have you checked your grounds and for
a chafed wire yet? Or is the barking of the newsgroup dogs starting
to get to you?

I have come to the conclusion to install a 100 watt

A good choice. Less draw and probably not too noticeable of a
difference in lumens (sp).