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The Builders Log

The record of an amateur-built aircraft’s construction, kept from a phone in the hangar.

The Builders Log records the construction of an aircraft as the work is done: each piece of work with its date, the task, who did it, photographs, and the parts it names with their part numbers and serial numbers. It is made for a phone in the hangar. Every page works the same on a computer.

A project’s pages are in the row under the bar, and on a phone in the bar at the bottom of the screen: Log (the entries), Plan (the sections of the build), Equipment (the equipment list) and Project (its details and the export). Projects lists every build on your account; a second project is started the same way as the first.

A project is an aircraft on your account from the day it is started. It is listed in MRO beside any aircraft you fly, marked Under construction, and its equipment is checked against airworthiness directives and manufacturer service documents while it is being built. A restoration, a rebuild, or a project begun by another builder is started the same way. An Upgrade (a new panel, avionics, an engine change) is a project of its own on an aircraft, with its own sections and its own Date completed; an aircraft can have as many as it needs, one after another or at once.

The Builders Log is part of the Hangar Flying membership. Without a membership a log can still be read and exported, whole, on any day; starting a project and adding to a log need the membership.

The log is evidence for the airworthiness inspection (14 CFR 21.191(g), AC 20-27G): what was fabricated and assembled, by whom, when, with photographs. Mark a photograph Builder shown working when it shows you doing the work.

Writing, signing and correcting an entry

An entry needs a date and a task; the rest can be added later. Signed, it is not changed.

Last day, beside the date, is for an entry that covers more than one day. The other fields are there when you want them: Work performed, Methods and materials, Plans page and step, Performed by, Hours, Kind of work (deburring, priming, riveting and the rest) and Lesson learned. Private entry keeps the entry out of anything shared later.

On a draft, beside Hours, the page says when its photographs were taken by the camera’s own clock (for example, 9:30 AM to 6:23 PM); the hours are still yours to write. A photograph taken as a session starts and another as it ends gives the session’s length: Use, under Hours, writes it in. A saved entry is a draft: it can be changed, photographs and parts can be added, and each photograph can be given a caption. A press on a photograph opens it large, with Caption, Download and Archive under it; Close returns to the entry. The three dots on a photograph’s corner offer the same. Move to another entry, among them, takes a photograph from one draft to another, its caption and pins with it. Add to equipment list, on a draft, opens the part form with the photograph of the part’s label beside it, so each box is typed, or read from the label for about 2 cents, and checked against it; a label that names two parts is added as two. Add a pin, on an opened photograph, puts a numbered dot on one spot with a note beside it: press Add a pin, press the spot, type the note, Save pin. Drafts are listed first on the Log page until they are signed. The Log page groups entries by month, and beside them (under them on a phone) lists the project’s sections, each with a link that narrows the log to it and a bar for how far along it is. Until you say for yourself on the Plan page, the bar is paler and reads “about”: it is worked out from your manual, as the share of the chapter your entries cite, and the Plan page offers it with a Use button, and the hours logged each month. Review drafts opens the oldest draft, and Next draft on each one goes to the one after. A draft’s section can be set from its row in the log. Use all, when suggested words are waiting, fills them into every draft at once; only blanks are filled. Join with another draft, at the foot of a draft, brings another draft’s photographs, hours and words into it. Move photographs to a new entry, under a draft’s photographs, does the opposite: the checked photographs become a draft of their own for the same day, with their captions and pins, when one day was really two jobs. Find pages, under Plans page and step, looks in your own manuals for what you wrote as the task and the work and lists the pages it most likely is; open each to check it, check the right ones, and Add the checked pages writes them into the box. It reads nothing new and costs nothing. Pins are drawn on the photographs in the copy of the log you download.

Sign entry, at the foot of a draft, takes your name and signs it. A signed entry is not changed. To put something right, open it and press Correct this entry: a new draft opens carrying the same words, and when it is signed the earlier entry is marked Superseded and stays in the log. Photographs can still be added to a signed entry.

Search the log finds entries by any words in them, including a part number or a serial number, and the two lists beside it narrow the log to one section or one kind of work.

Importing work you have not logged yet

Months of photographs become draft entries, one for each work day, by the photographs’ own dates.

Before making the entries you can put things where they belong. Merge with the day before joins two days that were one task: the entry then covers both, such as "12 Apr 2026 to 14 Apr 2026". To move photographs, check them, give the day and press Move. Leave checked out takes photographs out of the import; they are archived, not deleted. Back to their own days undoes a merge or a move.

A photograph with no date of its own, such as a scan or one that was sent in a message, is listed under No date: check it, give its day, and press Put the checked ones on this day. The same photograph brought in twice is kept once. An iPhone’s HEIC photographs are accepted.

Suggested words, on the same page, has the site read each draft’s photographs and propose its section, a task and what was done. Give it your own copies of the builder’s manuals (PDF) first if you have them, one at a time with Add this manual: each manual’s list of sections helps place each day’s work, and your copies are shown to nobody else. The page says how many drafts are waiting and what reading them costs before you press Suggest words. A limited number are read each day; the rest wait for the next.

A draft with a suggestion is marked Words suggested in the log. Open it: the suggestion is shown above the entry with Use these words, which fills in only what you have left blank, and Dismiss.

The entries made are drafts, and a suggestion is the reader’s description of photographs, not a record of what you did. Nothing is signed for you: open each one, correct it, and sign it when it is right.

Your manuals: reading them, searching them, opening a page

Your own copies of the kit’s manuals, read once, searchable, and linked from each entry.

A project keeps your own copies of the kit’s manuals as PDF files: the assembly manual, the parts manual, the figures. Add them on the Import page, under Suggested words, one at a time with Add this manual. They are shown to nobody but you.

Read the manuals through, on the same page, has the site read every page once. The page says what that costs before you press. A manual already read is not read again: the same file added to another project arrives read.

Manuals, in the row under the bar, searches everything read from them. Type the words of the job, such as "fuel cap drill guide"; each result names its manual and the page’s own number, and opens that page, with Previous page and Next page beside it.

On an entry, Plans page and step links to the manuals wherever it names a page they carry: a page number written as "page 70", a figure as "FIGURE 06-13", a parts manual page as "006D-02". Each link, and Open these pages beside them, opens one document of every page the reference names, in a window of its own.

Parts and the equipment list

A part entered once is on the aircraft’s equipment list, in the Builders Log and in MRO.

On a draft entry, Add a part takes the manufacturer, the model or description, the part number and the serial number. Equipment list says what the part is to the aircraft: Installed on the aircraft, Planned, not installed yet, or Not equipment for hardware and material the entry only names.

A part recorded as installed is on the aircraft’s equipment list from that moment, dated by the entry, and is checked against airworthiness directives and manufacturer service documents. It is the same list MRO keeps, so nothing is entered again when the aircraft flies.

The project’s Equipment page shows what is installed and what is planned. Add equipment records a part without an entry. A planned unit, from a panel design or entered here, becomes installed with Record as installed, which takes its serial number and the date. The engine and the propeller are recorded on their own pages, linked from there.

To start the list from a panel design, open the design in the Panel Designer and choose Add to my build. Its instruments arrive as planned.

The plan, and taking the log with you

Sections in the order you build, and a download of every entry and photograph.

Plan lists the sections of the build. A new project starts with Shop preparation, Delivery or pickup, and the main assemblies. Change, on a section, renames it, gives it the number the plans use, moves it up or down, or removes one that has no entries. Add a section is at the foot of the page. Mark complete dates a finished section; each section shows its entries and hours.

Export, on the Project page, downloads the whole log as a ZIP file: log.html to read or print, log.json for another program, and every photograph in a folder, named by the date of its entry. A large log comes as several files. The export is yours on any day.