Cessna 172 Electrical Problem

The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)

First check if there's power to the lamp. If so, you may want to pull
out the parts book and see if all the bushings and grommets for the
entire housing are present and in good shape. Many times vibration
will kill the bulb. Good luck and keep us posted of your findings.

On Fri, 12 Sep 2003 21:08:27 GMT, Chick Urick
wrote:

The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)

AFIK, the N model is 24V. Make sure that you are putting in a 24V
sealed beam (Not a 12V 4509).

If the voltage is correct, the only other reason that the lamp would
blow is vibration. Wiring problems, shorts, or rubbed through wire
insulation would not cause the lamp filament to blow; rather wiring
problems would cause the breaker to trip, preventing the lamp from
lighting until the short is corrected, & the breaker is reset.

Is the lamp mounted in the lower cowling on your model? If so, then a
prop balance may be in order.

MikeM
Skylane '1mm (with landing/taxi lights in the wing l. e. Thank God!)



On Fri, 12 Sep 2003 21:08:27 GMT, Chick Urick
wrote:

The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)

Vibration is biggest factor. The engine settles in its rubber mounts
and begins to hammer on the rubber bumper in the cowling, shaking the
daylights out of the bulb filament. Some operators turn the bulb 90°
to get the filament vertical, where it resists the vibration better.
Voltage regulator might be haywire, too, overheating the filament
(among other damage to the rest of the airplane's systems).
There are quartz versions of many of these bulbs, and they last
far longer than the old style. A few more bucks, but well worth it.

Dan

mikem wrote in message . ..
AFIK, the N model is 24V. Make sure that you are putting in a 24V
sealed beam (Not a 12V 4509).

If the voltage is correct, the only other reason that the lamp would
blow is vibration. Wiring problems, shorts, or rubbed through wire
insulation would not cause the lamp filament to blow; rather wiring
problems would cause the breaker to trip, preventing the lamp from
lighting until the short is corrected, & the breaker is reset.

Is the lamp mounted in the lower cowling on your model? If so, then a
prop balance may be in order.

MikeM
Skylane '1mm (with landing/taxi lights in the wing l. e. Thank God!)



On Fri, 12 Sep 2003 21:08:27 GMT, Chick Urick
wrote:

The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)

I had the same problem with a 172M. Both regular and quartz lamps lasted
one flight. I did the following:

1. Dynamic balance of the prop.
2. Turn the lights 90°. You may have to modify or fabricate the backing plates
to do this as the lamps have a keying lug. Also be aware that the light pattern
is about 12° wide x 6° high. Turning the lamps changes the illumated area, but I
didn't find any problems, particularly because I still had light!

Now, both regular and quartz lamps last many, many hours.

Good luck.

Tyler

I am now using

Dan Thomas wrote:
Vibration is biggest factor. The engine settles in its rubber mounts
and begins to hammer on the rubber bumper in the cowling, shaking the
daylights out of the bulb filament. Some operators turn the bulb 90°
to get the filament vertical, where it resists the vibration better.
Voltage regulator might be haywire, too, overheating the filament
(among other damage to the rest of the airplane's systems).
There are quartz versions of many of these bulbs, and they last
far longer than the old style. A few more bucks, but well worth it.

Dan

mikem wrote in message . ..

AFIK, the N model is 24V. Make sure that you are putting in a 24V
sealed beam (Not a 12V 4509).

If the voltage is correct, the only other reason that the lamp would
blow is vibration. Wiring problems, shorts, or rubbed through wire
insulation would not cause the lamp filament to blow; rather wiring
problems would cause the breaker to trip, preventing the lamp from
lighting until the short is corrected, & the breaker is reset.

Is the lamp mounted in the lower cowling on your model? If so, then a
prop balance may be in order.

MikeM
Skylane '1mm (with landing/taxi lights in the wing l. e. Thank God!)



On Fri, 12 Sep 2003 21:08:27 GMT, Chick Urick
wrote:


The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)

I have had much better success with the conventional filiment than with the quartz in my nose light (piper PA32).
Vibration knocks the internal bulb off the posts in short order on the Halogens. I now have Quartz lights on my
wingtips and a conventional bulb in the nose

Tyler Parsons wrote:

I had the same problem with a 172M. Both regular and quartz lamps lasted
one flight. I did the following:

1. Dynamic balance of the prop.
2. Turn the lights 90°. You may have to modify or fabricate the backing plates
to do this as the lamps have a keying lug. Also be aware that the light pattern
is about 12° wide x 6° high. Turning the lamps changes the illumated area, but I
didn't find any problems, particularly because I still had light!

Now, both regular and quartz lamps last many, many hours.

Good luck.

Tyler

I am now using

Dan Thomas wrote:
Vibration is biggest factor. The engine settles in its rubber mounts
and begins to hammer on the rubber bumper in the cowling, shaking the
daylights out of the bulb filament. Some operators turn the bulb 90°
to get the filament vertical, where it resists the vibration better.
Voltage regulator might be haywire, too, overheating the filament
(among other damage to the rest of the airplane's systems).
There are quartz versions of many of these bulbs, and they last
far longer than the old style. A few more bucks, but well worth it.

Dan

mikem wrote in message . ..

AFIK, the N model is 24V. Make sure that you are putting in a 24V
sealed beam (Not a 12V 4509).

If the voltage is correct, the only other reason that the lamp would
blow is vibration. Wiring problems, shorts, or rubbed through wire
insulation would not cause the lamp filament to blow; rather wiring
problems would cause the breaker to trip, preventing the lamp from
lighting until the short is corrected, & the breaker is reset.

Is the lamp mounted in the lower cowling on your model? If so, then a
prop balance may be in order.

MikeM
Skylane '1mm (with landing/taxi lights in the wing l. e. Thank God!)



On Fri, 12 Sep 2003 21:08:27 GMT, Chick Urick
wrote:


The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)


--
--Ray Andraka, P.E.
President, the Andraka Consulting Group, Inc.
401/884-7930 Fax 401/884-7950
email
http://www.andraka.com

"They that give up essential liberty to obtain a little
temporary safety deserve neither liberty nor safety."
-Benjamin Franklin, 1759

Cessna has or at least had a kit for the 172M 20 years ago that
stiffened and changed the resonant frequency of the nose bowl to stop
the landing lamps from blowing in just a few hours. The kit was a
hunk of honey comb, some fiber glass cloth and some epoxy that you
glued inside the bottom nose bowl. It sure worked on my plane. I
now get years out of a landing light instead of 2 to 3 flight hours.

On Sat, 13 Sep 2003 10:56:41 -0700, Tyler Parsons
wrote:

I had the same problem with a 172M. Both regular and quartz lamps lasted
one flight. I did the following:

1. Dynamic balance of the prop.
2. Turn the lights 90°. You may have to modify or fabricate the backing plates
to do this as the lamps have a keying lug. Also be aware that the light pattern
is about 12° wide x 6° high. Turning the lamps changes the illumated area, but I
didn't find any problems, particularly because I still had light!

Now, both regular and quartz lamps last many, many hours.

Good luck.

Tyler

I am now using

Dan Thomas wrote:
Vibration is biggest factor. The engine settles in its rubber mounts
and begins to hammer on the rubber bumper in the cowling, shaking the
daylights out of the bulb filament. Some operators turn the bulb 90°
to get the filament vertical, where it resists the vibration better.
Voltage regulator might be haywire, too, overheating the filament
(among other damage to the rest of the airplane's systems).
There are quartz versions of many of these bulbs, and they last
far longer than the old style. A few more bucks, but well worth it.

Dan

mikem wrote in message . ..

AFIK, the N model is 24V. Make sure that you are putting in a 24V
sealed beam (Not a 12V 4509).

If the voltage is correct, the only other reason that the lamp would
blow is vibration. Wiring problems, shorts, or rubbed through wire
insulation would not cause the lamp filament to blow; rather wiring
problems would cause the breaker to trip, preventing the lamp from
lighting until the short is corrected, & the breaker is reset.

Is the lamp mounted in the lower cowling on your model? If so, then a
prop balance may be in order.

MikeM
Skylane '1mm (with landing/taxi lights in the wing l. e. Thank God!)



On Fri, 12 Sep 2003 21:08:27 GMT, Chick Urick
wrote:


The landing light in my 1979 Cessna 172N keeps blowing out. I have
replaced it 3 time and rarely use it. The past bulb hasn't been
lighted more than 3 minutes, max. I preflight and it is fine, went to
land - dark, no light. Perhaps a lose connection (I'll) check again
or possible a surge in the electrical system? Any thought would be
appreciated. Thanks C.Urick (VA)