Which log book?

[N941WR]

Which log book should I enter the following maintenance items?

1. Replaced defective EGT probe?
2. Replaced cracked baffle?
3. Changed out oil cooler?

I can make good arguments to log 2 and 3 in the airframe logbook because they are somewhat independent of the engine and I guess you could say the same for #1.

[rocketbob]

Airframe for all three.

[N941WR]

So, unless it is an actual engine part, it goes in the airframe log book. Works for me.

Big items like carburetor, ignition, fuel pump, etc. inspection/repair/replacement would all go in the engine log book. (I?m already doing that.)

Maintenance items like changing the spark plugs, plug wires, cleaning the air filter, oil changes, etc. would also go in the engine log book. (I?m already doing that as well.)

[PaulR]

So how important is it to have multiple log books? My former Cherokee had only one. It seems to me that my 9A with a FP prop should only need one. Is there a regulation or another compelling reason to have separate log books for the engine and the airframe?

[Mel]

There is no requirement for having multiple logbooks.

The reason most people keep a separate logbook for the engine is that often an engine will be removed from the airframe and installed on a different aircraft. This way the "engine" logbook can follow the engine without disruption of the aircraft log.

[fixnflyguy]

As an AP/IA, I make a lot of logbook entries that are not for "my" aircraft. In the scenareo above, be it my plane or a customers, I would likely make the entry in both logbooks. While a logbook is a legal means of keeping track of essential maintenance,it is also a roadmap for the aircraft and components life from birth to death. I have re-built many antiques, and also aircraft that have been built up from two or more salvaged aircraft. I have found that logbook entries can "keep or scrap" parts that are in the "grey" area, and it also shows attention to detail and accuracy of repair/parts tracking for a prospective buyer if you ever sell.

[Mel]

Just to add to what Bill says, The quality of the entry can also make a big difference. i.e. A logbook entry that simply states, "Overhaul completed this date" conveys little information, whereas and entry that lists the parts that were replaced, the parts that were reconditioned, and to what tolerance, the manual to which the overhaul was performed, etc. can make a real difference.

[rocketbob]

Originally Posted by fixnflyguy

As an AP/IA, I make a lot of logbook entries that are not for "my" aircraft. In the scenareo above, be it my plane or a customers, I would likely make the entry in both logbooks.

I would not do this. Simply because it increase the noise level of whats in the logbook when a mechanic follows up to see whats been done to an engine historically, eg. if AD's have been complied with and proof of compliance.

As far as having one logbook goes, I would not do that either because there is value in an engine with its own logbook financially if the aircraft were ever parted out. Also it makes for a clean separation when looking thru the logbooks to see what has been done in the past to it.

I often look thru logbooks that are 30 to 50 years old, verifying AD compliance is bad enough as it is. And if I can't easily verify...then I have to physically check.

An AD compliance sheet summarizing what/when/how they were complied with is always very helpful and something I do as a matter of practice.

[David Paule]

I've found it helpful to look at the engine parts catalog and (for my certified airplane) the aircraft parts catalog when making the decision as to which logbook to enter something.

Turns out pretty much everything that's not "inside" the engine is in the aircraft parts catalog.

Dave

[Andrew M]

Duplicate entries of serial numbered or time/calender tracked items can hep when the engine is replaced, but the components stay. This has saved me a few prop governor overhauls and 500 hr mag inspections. I don't know how use full this practice would be on a "fleet of one", but it sure sure can help when establishing component history when each component doesn't have its own logs.(cardex system)