Components and their lives

Components and their lives

From the FlyPack CAMO manual

Serialised items fitted to an aircraft, each with its own hours, its own limit, and the release document it was fitted against.

Aircraft → the aircraft → Components.

Why they are separate from the aircraft

Engine and propeller hours are not edited on the aircraft. They belong to the component and move with it: an engine that comes off one aeroplane and goes onto another takes its time since new and time since overhaul with it. Editing them on the aircraft would make the aircraft the record of something it does not own, and the figures would part company the first time anything was swapped.

The aircraft carries airframe hours, landings and cycles. Everything else on this tab carries its own.

The four kinds of life

A hard-time or life-limited component without a limit is refused:

"A hard-time or life-limited component needs a limit — hours, cycles or months. Without one it would never reach the due list."

That is the whole reason the field is mandatory: a limit nobody entered is not a component with no limit, it is a component that will never be reported as due.

A shelf-life component without an expiry date is refused the same way.

Reading the table

A part's own clocks — TSN, TSO, what is left — follow how your organisation writes an hour figure, so they may read 1,412:30 h instead. Its limits do not: a 2 000 h TBO is quoted from the manufacturer’s manual and stays decimal. See How hours are written.

The left edge of each row is striped: red past the limit, amber inside 50 hours, otherwise plain.

Fit component

Fit component, top right of the tab. Its subtitle shows the aircraft's current airframe hours, because that is the number this part's remaining life will be counted against.

The part

Its limit

Shown only where the life kind needs one. Hours, Cycles, Months — whichever the manual states; a part may carry more than one, and whichever runs out first governs. A shelf-life part is asked for its expiry date instead.

Its life so far

The last two are optional until a limit in months is given, at which point one of them is required — see "Counted from the fitment date" below.

The release document

This is the evidence the part was fit to fit. ML.A.501 does not permit fitting one without it, which is why it is on this form rather than something to attach afterwards — and it is what an audit asks for first.

Finally, Fitted on — the date it went on.

A component fitted from your own store is issued to the work pack rather than fitted here — see Stores. Issuing it carries the batch, the release document and the price across, so the same paperwork is not typed twice.

Edit and Remove

Edit corrects a fitted component's details. The descriptive half — description, ATA, position — changes freely. The rest is a correction and carries a mandatory reason, because the forecast and every removal on file are read against it:

"Changing the hours limit and the hours since overhaul is a correction to the component record, so it needs a reason. The forecast and every removal on file are read against these."

The release document is not editable at all. ML.A.501 makes it the authority under which the part went on, so a wrong one is corrected by removing the component and fitting it again against the right one — which leaves both facts on the record.

Remove

Why is not decoration: unscheduled removals are what the reliability screen counts, and a part robbed for another aeroplane is a different fact from one that failed.

A removed component is not deleted and cannot be edited afterwards:

"That component is not fitted to one of your aircraft. A component that has been removed is part of its history and is not edited."

That refusal is the design. The record of what was fitted, for how long, and what happened to it is the aircraft's history, and history that can be revised is not history.

A part removed to get at something else — and going back on when the job is done — goes through Part off an aircraft in Stores instead, which tags it to that registration so it cannot be fitted to another aeroplane by accident.

Where a component's remaining life is shown

Everywhere the rest of the due list is. A fitted component's life is forecast exactly as a programme task is, so it appears:

• in the Remaining column on this tab,
• on the aircraft's Overview, under Next events, labelled component life,
• in the counters at the top of that overview — Engine TSN, Engine TSO, To TBO (the hours limit less the time since overhaul, or on condition where there is no limit), Propeller TSN and Propeller TSO, which are the component's own clocks and not the airframe's,
• on the dashboard due list, with Component · before the part number, and counted into the Overdue items and Due soon tiles,
• in the fleet list's one-line headline for the aircraft,
• in the nightly digest, under Past its limit or Due within N days,
• as a blocker on the airworthiness review — a part past its life is an item past its limit under ML.A.903, and stops a certificate being issued.

A component past its life grounds the aircraft, in the same way an overdue inspection does. The grounding reason names the part and its serial number.

It is also offered on the work-pack builder, ticked when it is already past its limit. Signing one off asks what was actually done to the part and does it — see Work packs and estimates, "Signing off a component".

Remaining counts whichever limit runs out first

Hours, cycles or calendar months — the one with the least left governs, and the column says which. There is no tolerance on a life limit: a part past its limit is unserviceable, not "inside the band".

Which clock a limit is measured against depends on the kind:

A shelf-life expiry is simply another calendar limit, and the earlier of it and the months limit governs.

On condition in that column means what it says: nothing limits this part.

The stripe

Red past the limit, amber inside the warning window — 25 hours or 30 days, the same window the rest of the due list uses — otherwise plain.

"Counted from the fitment date"

A calendar limit needs a day to count from, and the two that mean something are the day the part was made and the day it was last overhauled. Both are on the Form 1, and a limit in months now requires one of them:

"A limit in months has to be counted from somewhere. Record when the part was made, or when it was last overhauled — counting from the day it was fitted would report it due long after it expired."

Records written before that rule have neither, and the only date left is the fitment. That is later than the day the part was made, so the date shown is generous — a part made in 2019 and fitted in 2024 has already spent five years of a limit that now looks like it starts in 2024. An amber banner at the top of this tab names every component in that position. Edit each one and put the real date in.

Engine and propeller hours on the header

The aircraft's header carries, for the first engine and the first propeller fitted, without opening this tab:

They come from the fitted components rather than from the aircraft, and an engine's TSN and TSO reading the same figure is what a factory-new engine looks like; the two parting company is what an overhaul looks like — a propeller overhauled last month reads 3,411:54 h TSN and 0:00 h TSO on the same card row. Beside them, under the type name, is the type's own record — designator, TCDS, ELA class — which belongs to every aeroplane of the model and is corrected on Aircraft types.

Two different things sitting two lines apart, so it is worth being plain: an engine's hours are this aeroplane's, and the TCDS is the model's.

Parts on the shelf are a different question

Expiry on stock that has not been fitted is in Stores, which has its own Expiring filter and its own tiles. This tab is only about what is bolted to the aeroplane.