Work Orders and Maintenance Tracking for General Aviation

If your FBO has a maintenance shop, work orders are how you track what gets done, who did it, how long it took, and what it cost. A work order that exists only on paper - or worse, only in a mechanic's head - is a work order that is going to cause problems. Unbilled labor, missing parts charges, and disputes over what was authorized all trace back to poor work order management.

I have been building FBO software with maintenance shop modules since the late 1990s. The shops that run well are the ones that treat work orders as the primary record of everything that happens in the hangar. The shops that struggle are the ones where work orders are an afterthought - something that gets filled out at the end of the week so the front office can send an invoice.

Creating a Work Order

A work order starts when a customer requests service. It might be a scheduled annual inspection, an unscheduled squawk repair, an avionics installation, or a simple oil change. Regardless of the scope, the process begins the same way: a work order is opened in the system.

The work order header captures the essential information: the customer, the aircraft (tail number, make, model, serial number), the date opened, the requested service description, the current tach or Hobbs time, and who authorized the work. That last point - authorization - is critical. You should never start work without documented customer authorization, and the work order is where that authorization lives.

For larger jobs, the work order should include an estimate. The estimate breaks down the expected labor hours by category, the anticipated parts and materials, and any subcontracted work (like a prop shop or paint shop). The customer approves the estimate, and the work order becomes the document that tracks actual costs against the estimate.

Work Order Numbering

Every work order needs a unique identifier. Most shops use a sequential number, sometimes with a year prefix (2026-0147, for example). The numbering should be automatic - you do not want mechanics choosing their own work order numbers. The system should generate the next number in sequence when a new work order is created.

Tracking Labor Hours and Rates

Labor is typically the largest component of a maintenance invoice, and tracking it accurately is essential for both billing and shop management.

Rate Categories

Most maintenance shops have multiple labor rate categories. A common setup includes a standard airframe and powerplant (A&P) rate, a higher rate for inspections performed by an Inspection Authorization (IA) holder, an avionics rate (which is typically the highest), and sometimes a lower rate for apprentice or supervised work. The software needs to support multiple rate categories and apply the correct rate based on the type of work being performed.

Time Entry

Mechanics log their time against specific work orders. Each time entry should capture the mechanic's name, the work order number, the date, the start and stop times (or total hours), and a description of the work performed. Some shops use clock-in/clock-out time tracking, while others use manual hour entry. Either way, the software should make time entry fast and simple - if it takes five minutes to log 30 minutes of work, mechanics will not do it.

The description field matters more than most shops realize. When a customer questions a charge six months later, the time entry descriptions are what you have to justify the billing. "Worked on engine" is not helpful. "Removed and inspected #3 cylinder per compression test results, replaced exhaust valve and re-seated" tells the customer exactly what they are paying for.

Flat Rate vs. Actual Time

Some jobs are billed at a flat rate regardless of actual time spent. An oil change might be billed at 1.5 hours whether the mechanic finishes in 45 minutes or takes 2 hours. The software should support both flat-rate and actual-time billing on the same work order, because a single work order might include flat-rate items (the oil change) and actual-time items (troubleshooting a squawk found during the oil change).

Parts Inventory and Materials

Parts tracking serves two purposes: making sure you bill the customer for every part used, and making sure you know what is on your shelves.

Parts Used on Work Orders

When a mechanic uses a part on a job, it should be recorded against the work order immediately. The entry should include the part number, description, quantity, cost (what you paid), and price (what you are charging the customer). The markup on parts is a significant profit center for most shops, and the software should apply your standard markup automatically while allowing overrides for special pricing.

Parts that come from your own inventory should be deducted from stock when they are added to the work order. Parts that are ordered specifically for the job should be tracked as ordered, received, and installed - with the order date, vendor, and cost recorded for reference.

Inventory Management

A maintenance shop's parts inventory is typically a mix of high-turnover consumables (oil, filters, spark plugs, safety wire) and slower-moving components kept for common repairs. The software should track quantity on hand, reorder points, preferred vendors, and cost history for each part number.

Physical inventory counts should be supported - periodically counting what is actually on the shelf and comparing it to what the system says should be there. Discrepancies indicate parts that were used but not recorded against a work order (meaning lost revenue) or parts that were received but not entered into inventory.

Core Returns

Many aviation parts are sold on an exchange basis - you buy a rebuilt component and return the old one (the core) for a credit. The software should track core returns: which cores are pending return, the core charge amount, and the deadline for returning the core to avoid losing the credit. Missing a core return deadline can cost hundreds or thousands of dollars on components like magnetos, starters, and alternators.

Status Workflow

A work order moves through several statuses during its life, and the status should be visible to everyone who needs to know.

Typical Status Flow

Open: The work order has been created and work has not yet begun. The customer's request is documented, and the job may be waiting for scheduling, parts, or hangar space.

In Progress: A mechanic is actively working on the job. Time is being logged against the work order. This status tells the front counter that the aircraft is in the shop and not available for the customer.

Waiting on Parts: Work has been paused because a needed part is on order. This status is important for managing customer expectations and for shop scheduling - the bay or hangar space may need to be used for another aircraft while waiting.

Waiting on Customer Approval: Additional work was discovered during the job (a common occurrence during inspections), and the customer needs to approve the additional scope and cost before the mechanic can proceed.

Complete: All work has been performed, all time and parts have been recorded, and the mechanic or IA has signed off. The work order is ready to be invoiced.

Invoiced: The work order has been converted to an invoice and sent to the customer or applied to their account.

The software should enforce logical status transitions. You should not be able to mark a work order complete if there are no labor entries. You should not be able to invoice a work order that is still in progress. These guardrails prevent errors and ensure that every completed work order has the data needed for accurate billing.

Connecting Work Orders to Invoices

The final step in the work order lifecycle is turning it into a customer invoice. This is where the maintenance shop connects to the FBO's financial system.

When a work order is marked complete, the software should generate an invoice that itemizes all labor (broken down by rate category with descriptions), all parts and materials (with part numbers, quantities, and prices), any subcontracted work, and applicable taxes. The invoice should reference the work order number so the customer can cross-reference it with the estimate they approved.

For FBOs where the maintenance shop is part of a larger operation, the work order invoice should flow into the same accounts receivable system as fuel sales, hangar rent, and other services. The customer should see one statement that includes all charges, not separate bills from different departments.

Some customers have multiple aircraft, and you may have multiple open work orders for the same customer at the same time. The software should allow you to invoice work orders individually or batch them together, depending on the customer's preference and your billing cycle.

Maintenance Scheduling

Beyond individual work orders, the shop needs a scheduling view that shows what is coming up. Scheduled maintenance events - annuals, 100-hour inspections, AD compliance, and time-limited component replacements - can be tracked by both calendar date and tach or Hobbs time.

For aircraft that the FBO manages (either owned or on a management contract), the software should maintain a maintenance schedule that alerts the shop manager when upcoming events are approaching. This allows you to proactively contact the aircraft owner, schedule the work, and order parts before they are needed.

Shop capacity planning is also important. If you have three bays and two mechanics, you can only have a limited number of jobs in progress at once. The scheduling view should show current and upcoming workload so the shop manager can plan realistically and give customers accurate timelines.

Reporting for Shop Management

The data captured in work orders feeds into reports that help manage the shop's profitability and efficiency. Key reports include labor utilization (billable hours vs. total hours worked), revenue by mechanic, parts markup analysis, average job duration by type, and work-in-progress (total value of open work orders). These reports tell you whether your shop is making money, which mechanics are most productive, and where your pricing might need adjustment.

Frequently Asked Questions