Cowl latch question

[Helensgrandpa]

What are the legal requirements for installing cowl latch pins/camlocks? Can this be logged as minor, or does it require an STC/Form 337 field approval?

[Bruce Fenstermacher]

Assuming you are talking about a '52 or earlier cowl.

If you are going to add pins, screws or camlocks to the original latches to insure they do not come unlocked or to secure the door in addition to the original latches, I consider that a minor alteration. But a necessary one. I won't fly any such cowling without at least the front two latches so supplemented.

If your are talking about removing the original latch and replacing it with pins, screws or camlocks such as the STC's "Dip Davis" latch mod, I haven't given it much thought if that would meet the definition of a major alteration. Just because a mod has an STC does not mean it meets the definition of a major alteration. It means the person who did the mod wanted to illuminate any doubt as to the path of approval of the mod. The FAA has granted many STCs to mods that do not meet the definition of a major alteration.

[GAHorn]

Assuming you are talking about a '52 or earlier cowl.

If you are going to add pins, screws or camlocks to the original latches to insure they do not come unlocked or to secure the door in addition to the original latches, I consider that a minor alteration. But a necessary one. I won't fly any such cowling without at least the front two latches so supplemented.

If your are talking about removing the original latch and replacing it with pins, screws or camlocks such as the STC's "Dip Davis" latch mod, I haven't given it much thought if that would meet the definition of a major alteration. Just because a mod has an STC does not mean it meets the definition of a major alteration. It means the person who did the mod wanted to illuminate any doubt as to the path of approval of the mod. The FAA has granted many STCs to mods that do not meet the definition of a major alteration.

The modification of an airplane using an STC requires a Form 337, Major Alteration or Modification.

A “minor alteration” never requires a Form 337, nor is one appropriate, is my understanding.

(An instrument panel re-design, performed by a guy who became officially known by his job at FTW-FSDO as a Maintenance Inspector, actually used a Form 337 to document the change..AND… ON THAT 337 …stated “I consider this to be a Minor Alteration”.

Go figure.

(This would be the same inspector who refused to issue a Ferry Permit to fly an airplane with the retractible gear locked in the down position.)

[Bruce Fenstermacher]

Assuming you are talking about a '52 or earlier cowl.

If you are going to add pins, screws or camlocks to the original latches to insure they do not come unlocked or to secure the door in addition to the original latches, I consider that a minor alteration. But a necessary one. I won't fly any such cowling without at least the front two latches so supplemented.

I could have better stated it this way. If you are going to add pins, screws or camlocks to the original latches to insure they do not come unlocked or to secure the door in addition to the original latches using the common simple methods I've seen, documented several places in these forums, I consider that a minor alteration. It should be stated that if your favorite tool is a sawsall, any minor modification can become a major alteration.

If your are talking about removing the original latch and replacing it with pins, screws or camlocks such as the STC's "Dip Davis" latch mod, I haven't given it much thought if that would meet the definition of a major alteration. Just because a mod has an STC does not mean it meets the definition of a major alteration. It means the person who did the mod wanted to illuminate any doubt as to the path of approval of the mod. The FAA has granted many STCs to mods that do not meet the definition of a major alteration.

As George pointed out a STC is by it's nature, considered a major alteration, and requires a 337 be completed to document the change. But unfortunately the existence of an STC is not an indicator the modification meets the definition of a major alteration. I did not mean to say whether the "Dip Davis" mod did or did not meet the criteria of a major alteration.