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Thread: Landing light and PMA parts questions.

  1. #11

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    Default Re: Landing light and PMA parts questions.

    Quote Originally Posted by Jeff J View Post

    The electrical part is more ambiguous because a person must decide if it is a redesign of the system to add that circuit. It is great that Aeroleds were used in the example above but if the mod is done with that low amp draw in mind and for some reason an incandescent bulb gets installed because it is $400 cheaper there will be problems. Hopefully just a tripped breaker but could result in cooked wires and even fire. I had an owner come to me a while back who had installed a 100w bulb in the 50w taxi light position and couldn't figure out why his lights only worked about 30 seconds before the breaker tripped.
    Jeff, to duplicate the original you will need to use 18ga wire, which will prevent your scenario from happening. The main difference is you will want to use shielded wire, thankfully available in an 18/3 option.

  2. #12
    Administrator Steve Pierce's Avatar
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    Default Re: Landing light and PMA parts questions.

    Quote Originally Posted by Jeff J View Post
    I looked through the flow chart in AC 3-210A and didn't see anything that would change my mind on the light unless cutting that size of a hole in the leading edge would have no effect on the structural strength of the wing or negatively affect the flight characteristics. The definitions in the FAR are pretty clear that if it is improperly done and could affect either then it is a major alteration and/or repair.

    The electrical part is more ambiguous because a person must decide if it is a redesign of the system to add that circuit. It is great that Aeroleds were used in the example above but if the mod is done with that low amp draw in mind and for some reason an incandescent bulb gets installed because it is $400 cheaper there will be problems. Hopefully just a tripped breaker but could result in cooked wires and even fire. I had an owner come to me a while back who had installed a 100w bulb in the 50w taxi light position and couldn't figure out why his lights only worked about 30 seconds before the breaker tripped.
    Piper cut the holes and designed the opening and light cover. As far as someone putting an incandescent bulb in place of an LED where the wire is sized for the LED that is where the Instructions for Continued Airworthiness would come into play. I use shielded wire from Aero LED in rebuilds and document the installation so no one will do just what you described.

    One of the guys who worked here split the Piper landing light and put one bulb in each wing when he rebuilt his wings. Makes the wig wag really stand out and get you noticed and saved weight. I maintain a PA12 that has the standard double light in each wing. With the Maxpulse installed it really stands out.

  3. #13

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    Default Re: Landing light and PMA parts questions.

    Sorry, I didn’t realize Piper cut the holes in both wings. I don’t remember seeing that on the couple of naked airplanes I have seen. I don’t think I have ever seen an ICA for anything that wasn’t a major alteration.

    One thing I have noticed is that many people, including myself from time to time, seem to forget not all major alterations require an STC or field approval. If you already have approved data you don’t need either but a 337 still needs to be generated. The most readily available example I can think of is converting an engine from one model to another. For example, converting a Lycoming from constant speed to fixed pitch (SI 1435).

    In the end it is up to the mechanic doing the work and his/her relationship with the piece of government they answer to.
    "Good judgement comes from experience, and experience comes from bad judgement." - Fred Brooks

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    Default Re: Landing light and PMA parts questions.

    I don't know of Piper installing the landing light in both wings but it is their data on the structure.

  5. #15

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    Default Re: Landing light and PMA parts questions.

    Quote Originally Posted by Steve Pierce View Post
    Piper cut the holes and designed the opening and light cover. As far as someone putting an incandescent bulb in place of an LED where the wire is sized for the LED that is where the Instructions for Continued Airworthiness would come into play. I use shielded wire from Aero LED in rebuilds and document the installation so no one will do just what you described.
    .
    I would put a placard in the fixture as well. Looking at the chart in AC 43.13, 18 gauge wouldn't come close to handling the draw of incandescent lights (one 50w taxi light would work...barely) and the person who did the mod will get the blame if badness ensues.

    Are you writing the ICA into the log book as part of the maintenance entry? The ICA both OKC and St Louis want is 16 items long and, even when most are marked N/A, take a lot of space.
    Last edited by Jeff J; 11-30-2018 at 10:29 AM.
    "Good judgement comes from experience, and experience comes from bad judgement." - Fred Brooks

  6. #16

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    Default Re: Landing light and PMA parts questions.

    I'm pretty sure an 18ga wire is good for 10 amps, but I'm too lazy to read the chart A 100w bulb is what, 8 amps, but maybe the distance is an issue? Anyways....with Aeroleds it doesn't matter and like Steve said it is all documented so if the next person drops a 4509 in there it is on them. Perhaps the placard would be a good idea to idiot-proof it. All I will say is that those double Aeroleds in each wing will get your attention from a LONG way out

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    Default Re: Landing light and PMA parts questions.

    I noted the change in the wing rebuild 337 along with all of the other mods. Placard at the bulb is probably a good idea. The nice thing about LEDs is the y last almost forever. Out of all the ones I have installed I have not had to replace any of them even after I knock the LED nav lights off on trees.

  8. #18
    Gilbert Pierce's Avatar
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    Default Re: Landing light and PMA parts questions.

    Quote Originally Posted by Steve Pierce View Post
    . Out of all the ones I have installed I have not had to replace any of them even after I knock the LED nav lights off on trees.
    So, you can always find them? I only find the broken pieces of mine.
    Last edited by Gilbert Pierce; 12-01-2018 at 09:29 AM.

  9. #19

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    Default Re: Landing light and PMA parts questions.

    Quote Originally Posted by pilot View Post
    I'm pretty sure an 18ga wire is good for 10 amps, but I'm too lazy to read the chart A 100w bulb is what, 8 amps, but maybe the distance is an issue? Anyways....with Aeroleds it doesn't matter and like Steve said it is all documented so if the next person drops a 4509 in there it is on them. Perhaps the placard would be a good idea to idiot-proof it. All I will say is that those double Aeroleds in each wing will get your attention from a LONG way out
    It is, if you are only going about 8 feet. 18ga is good for 4 amps out to 20 feet which is what the Aeroled instructions are base on. Closer to 7 amps than 8 amps if using 14v. It is a good mod. A person is hard pressed to not notice an aircraft on final when they are on. I no longer believe anything can be idiot proofed.

    I can't find anything in the regs that would allow me to cut a hole that big into a leading edge and call that a minor. The flow chart in AC43-210A is nice and it is easy to come to the conclusion the alteration is minor if the answer is "no" to every question but the AC is not regulatory and I do not understand why it differentiates between a repair and an alteration when evaluating airworthiness if improperly done. I had answered "yes" in a couple of places and skipped to the end because I was thinking of the potential bad before I got to the airworthiness evaluation when I looked at it the first time.

    I would still call it a major and file the 337 the same as any major repair or STC. The extra amount of time spent would be minimal because I would copy and paste the log entry to the 337. As an added bonus, the entry and the ICA becomes permanently on file and easily retrieved if the logs become lost or damaged.

    Maybe the potential bad isn't as bad as I think if it came apart in flight because it wasn't done correctly. I know I have put some pretty big dents in leading edges (stripped more than one wingtip light too) without a noticeable change in flight characteristics. I haven't ever had a big hole in a wing but I would expect it to be more critical on a fabric airplane than a metal one. I think there would be more potential for the skin to balloon and cause problems with airflow and drag.
    Last edited by Jeff J; 12-01-2018 at 09:58 AM.
    "Good judgement comes from experience, and experience comes from bad judgement." - Fred Brooks

  10. #20
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    Default Re: Landing light and PMA parts questions.

    Use the Piper drawing for the landing light in the left wing to get a field approval for the landing light in the right wing. Worked on several that had this done via field approval. Can't imagine if it works on one wing it can't work on the other.

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