The International Cessna 170 Association

Thanks Brian for the link. I tried a set of bulbs very similar to this on a vintage Waco and i did have issues with interference. It is interesting how they can work on one plane and not the next.

Thanks to all for info on success with Aeroled. I will call them manyana. I did get an immediate return authorization from Spruce for the ones in have. Good folks there!

Check out the NavStrobe Sextant LED lights. They're bright, easy to install, and create no electrical interference. They have a continuous mode and a strobe mode. They're neither cheap nor approved, but they work fantastically well.

goodair wrote:I have not seen any AeroLED replacement bulbs that are STCed. You can purchase an STCed replacement assembly as a whole unit, but we already have the piggyback strobe set up and this would not make sense. If AeroLED makes an STCed LED bulb for nav lights, I have not seen it. Am I missing something?

Just to try to clarify this matter:
STCs are Supplemental Type Certificates. This provides an alternative basis of approval for a modification from the original Type Certificate (such as the mfr'r of the airplane, in this case Cessna.) An example might be the installation of wingtip strobes. Since they were never installed by Cessna on a 170 you will need a STC to make an original installation. This is an alteration of the Type Design of the aircraft.

PMAs are Parts Manufacturing Approval. This provides a basis of approval to replace an original, specified Part.... with a replacement Part from a different Manufacturer. An example might be replacing a Grimes Nav Lamp with a Trinair, GE, or other mfr's …. OR... type of Lamp such as an LED to replace an incandescent. This does not alter the Type design of the aircraft.

goodair wrote:Thanks Brian for the link. I tried a set of bulbs very similar to this on a vintage Waco and i did have issues with interference. It is interesting how they can work on one plane and not the next.

Thanks to all for info on success with Aeroled. I will call them manyana. I did get an immediate return authorization from Spruce for the ones in have. Good folks there!

The difference might be that the Waco did not have it's lighting/wiring circuits nearby to the audio/avionics circuits while the Cessna ran them along the same route or tied them to the same Buss or had the audio/avionics wiring grounded more securely, or the circuit-noise was better-propagated by the all-metal structure of the Cessna, etc. (Another example of why some modifications require STCs which include detailed installation instructions and Continued-Airworthiness-Instructions..)

I actually ran a resoration shop for almost 25 years. We installed a bunch of STCs, and also did quite a few field approvals which in this day and age is no easy feat. I received a field approval on a Boeing Stearman for a 4 aileron installation and the paperwork weighed an honest 10 pounds. The issue here is the grey area about lightbulbs. Do a google on LED legality on aircrat. Its crazy. Our piggyback strobe assys are a legal installation through an STC, but the whole replacement LED bulb debate is actually rediculous. Are the original filament bulbs pma parts? You can get an china equivalent at an auto parts store. The bulbs are listed in the approved parts manual but is a specific brand required? Right now i believe the LED bulb would need to be a PMA approved part, even though it is unclear weather the original bulb even has pma approval. It is also grey or at least inclear to me weather or not an A&P can do a log book entry and "approve" the installation of a non pma part as some of the LED manufacturers are suggesting. It boils down to enforcement. If the FAA wants to have issues with these bulbs, they will. If they want to turn their heads and not address it then thats what they will do. I think for now its up to what your FAA inspecter feels like if one should be ramp checked for maintenance. Could go either way.

I am hoping that reasonable people will see the significant safety advantage these LED bulbs offer, especially to vintage aircraft with limited generating capabilities. These advantages include a drastic reduction in load on our generator/alternator systems and the reduction in heat generated by the old bulbs and higher amperage through the wires, amongst others.

Now, if they can only evercome this static issue....

My C195 landing light current draw went from 37amps with the original Par 64 bulbs to 7amps with the PMA'd LEDs

LEDs have taken over on Commercial aircraft. Likely the return on GA aircraft makes retro certs uneconomical . In another recent post I’m championing A STC route for a seat install. On this I’m jumping the fence. Common sense I think has to prevail, big difference in a seat rolling through the cabin and a burnt out bulb. I’d do the research on the downsides and decide your path.

I agree goodair that an LED replacement lamp for an incandescent is a good move in our airplanes (with specific regard to nav lamps. I"m not yet a fan of landing/taxi LEDs but that's another issue revolving around wave-length-visibility preference.)

As for installing a different mfr lamp legality: The OEM Parts List specifies the Part Number (which the OEM expects you to source just like you would any other airframe part... I.E., from them or some other aviation supplier who can provide traceability/pedigree. FAA/CAA approved that method.) For many years it was required to use that genuine part from that type supplier and the labor done by a genuine A&P. Rumors were rife about owners who were "violated" because they used a Wagner 4309 lamp instead of the genuine GE4309 for landing/taxi lamps. (I personally believe they were merely rumors of scaremongers.)

But...No longer. FAR 43 Appdx A provides for "preventive maintenance" which allows an owner/pilot to change lightbulbs (and certain other tasks.)

A PMA allows that owner/pilot to select a different maker's product instead of the OEM's Parts List. If that part happens to be a different design (such as a change from incandescent to LED) then that is also Kosher.

A few years ago FAA issued Advisory Circular 23-27 allowing aircraft built/certified before Jan 1, 1980 "for substantiating parts or materials substitutions to maintain the safety of old or out-of-production general aviation (GA) aircraft, or other GA aircraft where the parts or materials are either difficult or impossible to obtain."... in other words, to use common parts of "equal" quality such as automotive lamps as a substitute for the OEM part when supplies are limited or obsolete (such as incandescents can be claimed to be.

On top of all that.... it is a common perception that FAA Inspectors roam the countryside as Gestapo searching for owner/pilots who have made such substitutions in the hope of writing violations and issueing "Condition Tags" for parked aircraft on the line.

That is simply not true. Firstly, they have neither the time nor the inclination to actively go out and search for those kinds of minor issues. Secondly, unless there is some other reason to draw attention to oneself (like landing on the wrong surface, or without clearance, or some other blatant observation, or having an accident) it is unlikely that the Inspector will cast anything other than a sideways glance at you.
UNLESS it can be proven that the use of the LED lamp is the cause of the firey crash that killed the occupants it's unlikely that anything near to enforcement action will be taken with regard to such minor alterations. (Although the failure to record the installation by the installer is always a more serious matter in their eyes.)

It was not too long ago I was attacked by a forum participant for recommending an auto supply house for replacement wheel bearings. The person was adamant that only "aviation" bearings were legal. (I had actually replaced the nose wheel bearings on a Hawker jet with automotive parts while on a trip carrying the U.S. vice-president because the OEM Service Center didn't have the parts in stock and the departure was imminent. The Service Center inspector was beside himself with horror and threatened a report to FAA... who, the next week informed him the substitution was an approved action.) In fact, AC 23-27 specifies "BEARINGS. Bearing catalogs from general bearing supply houses state in their introductions that the bearings listed in their catalog meet ANSI (American National Standards Institute) specifications or exclusions. They also give cross-references. Usually, they list bearings for aviation applications. You must use the appropriate part from the cross-reference matrix.
Approval: This is a minor alteration and you may document it by a logbook entry. The logbook entry must reference the manufacturer's identification and industry specification for the original and replacement bearing. "
Needless to say, I recently preferred to purchase our 172 replacement nosewheel bearings from CARQUEST for $9.95/pair rather than those from my favorite aviation supplier for $57.90 each.

Have you had your annual inspector insist that you must not replace your original lead acid battery with a more modern Concord without an expensive approval basis?
Baloney. Show him AC23-27.

One can read AC 23-37 here: https://www.faa.gov/documentLibrary/med ... _23-27.pdf

I totally agree. I have used AC 23-27 on many occasions including some old parts on vintage aircraft such as fuel valves on old Waco's etc. This has been a great boon for us vintage folks. I also agree that there are things to worry about, and things NOT to. Being ramp checked and "busted" for having some LED bulbs is not going to be on my worry list.

I would however like to find some bulbs that do not cause interference over the audio. I am going to talk with the folks at AeroLED today to see if they have any input. It is very odd that some bulbs work ok, and others will cause this interference. I would like to know what is different in the bulbs so that we can shop with some useful knowledge. Right now its a pig and a poke....

Thanks to all for all the input. Great information.

I have been using the following LED bulbs for my nav lights and in the year I've had them, I have had zero issues with interference. You do need to file off one of the "pegs" on the base of the bulb (I used the 1156 base).

https://www.aircraftspruce.com/catalog/ ... -15810.php

This is really old thread (2010) but is a long discussion of when I first tried LED nav and interior lights before they were popular. They're still in my 170 and still work great and no avionics noise. YMMV (I recently ordered some additional LEDs from them for an automotive purpose so they're still in business. Please note that the red and green LEDs were necessary to avoid color-shift behind the original red/green nav lenses.)
http://www.cessna170.org/forums/viewtop ... nav+lights

Hi, just picked up my first Cessna 170B. I have a Cessna 140 but was getting tired of not being able to stretch out when flying.
The 170B I purchased was advertised as a 1953, however when looking at the serial number 26137 it appears it falls in the 1954 list. The copies of the original application for airworthiness from the CAA shows the dealer registration certificate Form ACA-1707 is dated 5-6-53. This same form ACA-305 (11-51) is dated 1/12/54 signed by Owner’s agent.
So do I have a 1953 or 1954 Cessna 170B?
Any info would be appreciated.

I think the answer is you have 1954 model year with a 1953 year of production. I think this like autos where you can buy next years model late this year. I have a 1953 model built in 1952.

That serial number is definitely 1954 model. Like cars, production and sales started later in the year before, but the month of May seems a bit early. By serial number, yours was the 99th 1954 model. Mine (sn 26541) was the 37th 170 produced as a 1955 model, and the factory weight and balance is dated in October of 1954.

I have never trusted those flimsy little "sash" chains, I used to install double chains on each side of the tailwheel. Anyone had problems with them breaking? I would think the heavy duty chain would work better especially if you are using a heavy duty spring

About twenty years here reading the forum. Breaking a sash chain is just not a problem.

I wonder what "heavy duty" springs you might be using and why?