Maintenance Billing Reference

PlaneConnection’s maintenance billing system calculates work order costs from configurable labor rates and parts markup rules, generates formal estimates, and tracks those estimates through approval and invoicing. This page is the technical reference for all billing configuration and lifecycle rules.

Billing configuration is managed in Maintenance > Billing Settings. For step-by-step setup instructions, see the billing settings how-to guide. For the API reference, see Maintenance API Endpoints.

Labor Rate Structure

Labor rates are defined per workspace and determine how technician time is priced on billing estimates. Each rate has a base hourly rate plus optional multipliers for overtime and AOG (Aircraft on Ground) situations.

Mechanic Types

Mechanic Type	API Value	Description
A&P Mechanic	`ap`	Airframe and Powerplant certificate holder. Standard maintenance labor.
IA Inspector	`ia`	Inspection Authorization holder. Higher rate reflecting inspection authority per 14 CFR 43.7.
Avionics	`avionics`	Avionics technician. Specialized rate for electronic and instrument work.
Sheet Metal	`sheet_metal`	Structural repair specialist. Rate for airframe structural work.
General	`general`	General labor (cleaning, ground handling, non-certificated tasks).

Rate Multipliers

Each labor rate includes two optional multipliers applied to the base hourly rate:

Multiplier	Default	Description
Overtime	1.5x	Applied to labor hours worked outside normal business hours.
AOG	1.5x	Applied when the work order priority is `aog` (Aircraft on Ground). Reflects the urgency premium for grounding events.

Effective cost calculation:

standard_cost   = hours x hourly_rate
overtime_cost   = hours x hourly_rate x overtime_multiplier
aog_cost        = hours x hourly_rate x aog_multiplier

Rate Configuration Fields

Field	Type	Required	Description
`rate_name`	String	Yes	Display name for the rate (e.g., “Standard A&P Rate”).
`mechanic_type`	Enum	Yes	One of: `ap`, `ia`, `avionics`, `sheet_metal`, `general`.
`hourly_rate`	Number	Yes	Base hourly rate in USD. Must be greater than zero.
`overtime_multiplier`	Number	No	Multiplier for overtime hours. Defaults to 1.5.
`aog_multiplier`	Number	No	Multiplier for AOG priority work orders. Defaults to 1.5.
`effective_date`	Date	Yes	Date from which this rate applies. Allows rate versioning.
`expires_at`	Date	No	Optional expiration date. Null means the rate is active indefinitely.
`is_default`	Boolean	No	If true, this rate is used when no specific rate is assigned to an estimate line item.

Only one rate per workspace should be marked as the default (is_default = true). When generating an estimate, the system uses the most recent default rate if no rate is explicitly assigned. If no default rate exists, a system fallback rate is applied.

Parts Markup Tiers

Parts markup rules define the profit margin applied to parts costs on billing estimates. Rules are configured as tiered cost ranges, allowing different markup percentages for different part price points.

How Markup Tiers Work

When an estimate is generated, each parts line item’s unit cost is evaluated against the markup rules in sort order. The first rule whose cost range matches the unit cost determines the markup percentage. Example tier structure: Markup tiers are fully configurable. A typical setup uses tiered cost ranges with higher markup percentages on lower-cost parts and lower percentages on major components. You can create as many tiers as needed to match your shop’s pricing strategy.

Markup Rule Fields

Field	Type	Required	Description
`rule_name`	String	Yes	Display name for the rule (e.g., “Small Parts 100%”).
`rule_type`	String	Yes	`parts_markup` for parts tiers, `shop_supplies` for shop supply charges.
`cost_floor`	Number	No	Minimum unit cost for this tier (inclusive). Null means no lower bound.
`cost_ceiling`	Number	No	Maximum unit cost for this tier (exclusive). Null means no upper bound.
`markup_percent`	Number	Yes	Percentage markup applied to unit cost.
`basis_type`	String	No	For shop supply rules: `labor_total` (percentage of labor) or `flat` (fixed amount).
`flat_amount`	Number	No	For flat-rate shop supply rules: the fixed dollar amount.
`sort_order`	Number	Yes	Evaluation order. Lower numbers are evaluated first.
`is_active`	Boolean	Yes	Only active rules are applied during estimate generation.

Shop Supply Rules

In addition to parts markup, operators can configure shop supply charges that cover consumables (safety wire, sealant, hardware, rags, etc.) not individually tracked as inventory items. Shop supply rules support two basis types:

Basis Type	Calculation	Example
`labor_total`	Percentage of total labor cost	5% of $2,000 labor =$ 100 shop supplies
`flat`	Fixed dollar amount per estimate	$75 flat shop supply charge

Billing Types

Each estimate is assigned a billing type that determines how the final invoice is calculated:

Billing Type	API Value	Description
Time and Materials	`time_and_materials`	Customer pays actual labor hours at the applicable rate plus actual parts cost with markup. The standard billing method.
Flat Rate	`flat_rate`	Customer pays a fixed price regardless of actual hours or parts consumed. Used for standard inspections or published service pricing.
Hybrid	`hybrid`	Combination of flat-rate labor and time-and-materials parts, or vice versa.
Not to Exceed	`not_to_exceed`	Time and materials billing with a maximum cap (NTE amount). Customer pays actual costs up to the NTE ceiling.

NTE (Not to Exceed) Amounts

When billing type is not_to_exceed, the estimate includes an nte_amount field representing the maximum the customer will be invoiced. If actual costs exceed the NTE amount, the operator absorbs the difference.

Estimate Statuses

Billing estimates follow a lifecycle from creation through customer approval to final invoicing.

Status	API Value	Description
Draft	`draft`	Estimate created and under internal review. Not yet visible to the customer.
Sent	`sent`	Estimate has been sent to the customer for review and approval.
Approved	`approved`	Customer has approved the estimate. Work may proceed or continue.
Rejected	`rejected`	Customer has declined the estimate. Work scope may need revision.
Invoiced	`invoiced`	Estimate has been converted to an invoice. Final billing record.

Estimate Lifecycle

Estimate Generation

When a billing estimate is generated for a work order, the system performs the following calculation:

Estimate Fields

Field	Type	Description
`estimate_number`	String	Auto-generated identifier (format: `EST-{unique_id}`).
`work_order_id`	String	Reference to the associated work order.
`billing_type`	Enum	One of: `time_and_materials`, `flat_rate`, `hybrid`, `not_to_exceed`.
`nte_amount`	Number	Maximum billable amount (NTE billing type only).
`labor_total`	Number	Sum of all labor line item costs.
`parts_total`	Number	Sum of all parts line item base costs (before markup).
`parts_markup_total`	Number	Total markup applied to parts.
`shop_supplies_total`	Number	Total shop supply charges.
`outside_services_total`	Number	Costs for outsourced work (vendor invoices).
`subtotal`	Number	Sum of all cost categories before tax.
`tax_rate`	Number	Applicable tax rate (decimal, e.g., 0.08 for 8%).
`tax_amount`	Number	Calculated tax amount.
`total_amount`	Number	Final estimate total including tax.
`customer_name`	String	Customer or aircraft owner name for the estimate.
`customer_email`	String	Customer contact email for estimate delivery.
`payment_terms`	String	Payment terms (e.g., “Net 30”, “Due on receipt”).
`notes`	Text	Internal or customer-facing notes.
`status`	Enum	Current estimate status (see Estimate Statuses above).

Billing Events

Every significant action on an estimate is recorded as a billing event for audit trail purposes:

Event Type	Description
`estimate_created`	New estimate generated from work order data.
`estimate_sent`	Estimate sent to customer.
`estimate_approved`	Customer approved the estimate.
`estimate_rejected`	Customer rejected the estimate.
`estimate_revised`	Estimate was modified after initial creation.
`invoice_created`	Estimate converted to a final invoice.
`payment_received`	Payment recorded against the invoice.

Work Order Statuses

Lifecycle of work orders that billing estimates are attached to.

Maintenance API Endpoints

REST API for creating rates, generating estimates, and retrieving billing data.

Maintenance Data Model

How billing fits into the broader maintenance data flow.

Financial Reports

Financial reporting that incorporates maintenance billing data.

SMS Reference

SmartScore

Operations Reference

FBO Reference

Maintenance Reference

Operational Reports

Portal Reference

Platform Reference

API Reference

Labor Rate Structure

Mechanic Types

Rate Multipliers

Rate Configuration Fields

Parts Markup Tiers

How Markup Tiers Work

Markup Rule Fields

Shop Supply Rules

Billing Types

NTE (Not to Exceed) Amounts

Estimate Statuses

Estimate Lifecycle

Estimate Generation

Estimate Fields

Billing Events

Work Order Statuses

Maintenance API Endpoints

Maintenance Data Model

Financial Reports

​Labor Rate Structure

​Mechanic Types

​Rate Multipliers

​Rate Configuration Fields

​Parts Markup Tiers

​How Markup Tiers Work

​Markup Rule Fields

​Shop Supply Rules

​Billing Types

​NTE (Not to Exceed) Amounts

​Estimate Statuses

​Estimate Lifecycle

​Estimate Generation

​Estimate Fields

​Billing Events

​Related

Work Order Statuses

Maintenance API Endpoints

Maintenance Data Model

Financial Reports

Labor Rate Structure

Mechanic Types

Rate Multipliers

Rate Configuration Fields

Parts Markup Tiers

How Markup Tiers Work

Markup Rule Fields

Shop Supply Rules

Billing Types

NTE (Not to Exceed) Amounts

Estimate Statuses

Estimate Lifecycle

Estimate Generation

Estimate Fields

Billing Events

Related