Unplanned maintenance events cost airlines an estimated $8 billion annually, not because aircraft wear out faster than expected, but because heavy check planning does not start early enough or run with enough precision. A D-check on a wide-body aircraft can exceed $10 million in direct costs and consume 50,000 labour hours over eight weeks, during which the aircraft generates zero revenue. The difference between a check that finishes within 5% of planned turnaround time and one that overruns by 20% is almost never a technical surprise. It is a planning failure. Operators with the best on-time performance and lowest cost-per-flight-hour treat every A-check, C-check, and D-check as an 18-month project with structured milestones, not an event that begins when the aircraft rolls into the hangar. This article breaks down the planning framework that separates best-in-class MRO operations from the rest, and how iFactory Check Planning Module gives your team the infrastructure to execute it.
iFactory Check Planning Module
From A-Check to D-Check: The Planning Discipline That Cuts TAT by 30%
Heavy maintenance checks are the most capital-intensive events in an aircraft's lifecycle. Every day of overrun costs six figures in penalties and lost revenue. iFactory Check Planning Module gives planners the structured milestone tracking, parts pre-positioning alerts, and live TAT burndown to deliver every check on time and on budget.
$8B
annual cost of unplanned maintenance events across the global airline industry, driven primarily by planning gaps rather than technical surprises
50,000
labour hours consumed by a single wide-body D-check, requiring 200+ specialised technicians working across multiple trades and shifts for up to 60 days
15-30%
typical TAT overrun for heavy checks without structured planning systems, compared to under 5% for operators using milestone-based planning frameworks
18 mo
planning horizon required for D-check success. Locking hangar slots and placing long-lead parts orders 12-18 months ahead reduces total check cost by 15-20%
The Check Spectrum: Four Levels, Four Planning Models
Each check type differs by an order of magnitude in scope, cost, duration, and planning lead time. Treating them all with the same planning approach is the fastest route to budget overruns and operational disruption.
A-Check
Every 400-800 FH
10-24 hours
$6K-$10K
Visual inspections, fluid checks, filter changes, emergency equipment verification. Completed overnight at the gate. Planning lead time: 2-4 weeks. Risks: task card accuracy and parts availability for minor consumables.
B-Check
Every 6-8 months
1-3 days
$50K-$150K
Deeper system functional tests, flight control checks, hydraulic and fuel system inspections, landing gear servicing. Requires dedicated hangar access. Planning lead time: 8-12 weeks. Risks: engineering order readiness and specialist trade availability.
C-Check
Every 18-24 months
1-3 weeks
$500K-$1.5M
Full structural inspection with panel removal, system deep-testing, corrosion treatment, component replacements, AD and SB compliance. Requires full hangar occupancy. Planning lead time: 3-6 months. Risks: findings management, concession control, mid-check scope creep.
D-Check
Every 6-10 years
4-8 weeks
$2M-$10M+
Complete aircraft strip to bare metal. Full corrosion inspection, wiring audit, structural repairs, landing gear overhaul, cabin refurbishment, avionics upgrades. Planning lead time: 12-18 months. Risks: long-lead parts, OEM coordination, engineering disposition delays.
The 18-Month Planning Timeline That Delivers On-Time Checks
Best-in-class MRO operators treat heavy checks as rolling projects with structured milestones. Every gate has a readiness target. When a milestone slips, the system alerts planners before the delay compounds into a TAT overrun.
18 mo
Hangar Slot & Fleet Calendar Lock
Secure facility slot against fleet schedule. Operators booking D-check slots on short notice pay 15-25% premium on facility rates. Every subsequent planning step depends on this anchor date.
12 mo
Long-Lead Parts Procurement
Identify all components with lead times exceeding 8 weeks. Issue purchase orders for structural hardware, avionics LRUs, landing gear components, and specialty consumables. This is the single most impactful action for preventing parts-caused TAT extension.
6-9 mo
AD & SB Compliance Review
Complete review of all applicable Airworthiness Directives, Service Bulletins, and Engineering Orders due at or before the check interval. Load all compliance items into the work package. Zero last-minute AD discoveries is the measurable goal.
3 mo
Condition Assessment & Scope Pre-Planning
Review asset condition scores, flight cycle data, previous check findings, and deferred defect log. Flag likely structural zones for enhanced inspection. Teams with condition-based scoring reduce mid-check scope extensions by up to 40%.
60-90 d
Work Package Finalisation
Engineering completes full job card package with parallel task allocation across zones and trades. Technician roster confirmed. Special tooling allocated. Pre-induction work package completion at 95%+ is the leading predictor of check TAT performance.
Day 0
Aircraft Induction & Execution
Parts kitted and confirmed. Job cards finalised. Technicians briefed. First tasks beginning within 2 hours of aircraft arrival. Structured planning delivers no waiting and no scrambling from the moment the aircraft enters the hangar.
Your next heavy check should not be a test of your team's ability to improvise. iFactory Check Planning Module gives you the milestone framework, readiness tracking, and pre-positioning alerts to turn every check into a predictable, measurable project. Start building your check plan today.
The Four Causes of TAT Overrun and How Structured Planning Eliminates Them
Industry data consistently identifies four root causes of heavy check TAT overruns. Each is a planning failure, not a technical mystery. Each is preventable with the right systems in place.
Cause 1
Undiscovered Structural Defects
Corrosion, cracking, and wear found during teardown that were not anticipated add an average of 18% to labour hours when no condition tracking is in place. iFactory Check Planning Module integrates asset condition history and previous check findings into the pre-induction scope assessment, flagging high-probability zones before the aircraft enters the hangar.
Cause 2
Long-Lead Parts Not Pre-Ordered
Aircraft wait in hangars on facility fees for components that should have been ordered 12 months earlier. Late parts are the single most common cause of critical path delays in base maintenance. iFactory maps procurement lead times against induction dates and generates pre-positioning alerts for every critical component weeks before the task hits the critical path.
Cause 3
Incomplete Work Packages at Induction
When engineering finalises job cards at induction rather than 60-90 days prior, technicians idle and parallel task planning becomes impossible. The industry benchmark is 95% work package completion before aircraft arrival. Manual systems typically achieve 60-70%. iFactory tracks work package readiness as a live percentage against each milestone date with automatic escalation for any gate falling behind.
Cause 4
Last-Minute AD and SB Discovery
Mandatory directives not loaded into the work package during the 6-9 month compliance review add unplanned scope that disrupts the entire task schedule. iFactory AD and SB tracking loads all applicable directives into the work package during planning, eliminating the last-minute compliance discoveries that routinely extend check duration by two to five days.
iFactory Check Planning Module: From Spreadsheets to Structured Execution
iFactory Check Planning Module replaces manual planning with a structured digital workflow that connects every task, part, resource, and record from the moment a check is scheduled to the moment the release certificate is signed.
01
Multi-Year Fleet Check Calendar
Visual timeline of every scheduled check across your fleet. A-checks through D-checks plotted against flying hours, calendar intervals, and hangar slot availability. Planners see conflicts before they become commitments.
02
Milestone Readiness Tracking
Every check has structured gates from 18 months out to induction day. Work package completion, parts pre-positioning, engineering order issuance, and facility coordination tracked as live percentages against target dates.
03
Findings Management Workflow
Every unplanned finding discovered during the check is logged, photographed, severity-scored, and assigned to an engineering disposition queue. Engineering responses tracked against SLA targets with automatic escalation for overdue items.
04
Live TAT Burndown Monitoring
Real-time view of task completion percentage by zone, trade, and work package. Critical path tasks flagged when slippage is detected. Maintenance control and customer representatives see the same live view simultaneously.
05
Parts Pre-Positioning Alerts
Correlate work package task cards with parts demand. Map procurement lead times against check induction dates. Generate automated alerts for any component without confirmed procurement or staging status before it reaches the critical path.
06
Audit-Ready Compliance Documentation
Every task sign-off, inspector stamp, AD compliance record, and concession approval lives in one traceable digital thread from check open to certificate filing. No paper chasing at check closure.
Frequently Asked Questions
What is the difference between planning an A-check and a D-check in iFactory?
The planning frameworks differ in horizon depth and milestone granularity. An A-check in iFactory requires a 2-4 week planning window with focus on task card accuracy and consumable parts availability. A D-check requires an 18-month planning horizon with structured gates for long-lead procurement, AD compliance review, condition assessment, and work package finalisation. iFactory Check Planning Module adapts the milestone template to the check type, so planners use the right level of structure for each event rather than a one-size-fits-all workflow.
How does iFactory handle unplanned findings discovered during a heavy check?
Every finding is logged at the point of discovery with photo, location data, and initial severity assessment through a mobile interface. The finding is automatically routed to the engineering disposition queue with SLA tracking. The work package is updated in real time with the new scope. The TAT burndown model recalculates the critical path impact and surfaces recovery options to the planner. The entire findings lifecycle from discovery to closure is visible to maintenance control, engineering, and quality assurance simultaneously, eliminating the paper backlog that stalls hangar operations.
What planning horizon does iFactory recommend for each check type?
iFactory recommends a planning horizon of 2-4 weeks for A-checks, 8-12 weeks for B-checks, 3-6 months for C-checks, and 12-18 months for D-checks. These horizons reflect the procurement lead times, engineering decision cycles, and resource coordination requirements specific to each check level. The platform enforces these minimum horizons through its milestone scheduling logic, preventing the common planning error of beginning preparation too close to the induction date.
Can iFactory manage multiple concurrent heavy checks across different hangar bays?
Yes. iFactory Check Planning Module supports multiple concurrent check events across hangar bays with independent TAT burndown, manhour tracking, findings queues, and compliance documentation per aircraft. The fleet calendar provides a consolidated view of all active and upcoming checks across every facility, enabling planners to identify resource conflicts, bay contention, and labour bottlenecks before they impact scheduled delivery dates. This multi-check visibility prevents the cascading delays that occur when an overrunning D-check displaces the next aircraft in the bay schedule.
How does iFactory integrate with existing maintenance and engineering systems?
iFactory Check Planning Module connects with existing maintenance management systems, engineering databases, procurement platforms, and scheduling tools through pre-built API connectors and file-based import. The normalisation layer maps data from each source to a common check planning taxonomy, standardising task classifications, parts catalogues, and compliance records across systems that previously used incompatible formats. This means your engineering team keeps working in the tools they know while iFactory provides the planning orchestration layer that connects every dataset into a single check execution view.
iFactory Check Planning Module
The Check Starts 18 Months Before the Aircraft Arrives
iFactory Check Planning Module gives your planning team the structured milestone framework, live TAT burndown, findings management, and parts pre-positioning alerts to deliver every heavy check on time and on budget. From A-check to D-check, across your entire fleet.
Trusted by airline engineering teams, MRO compliance departments, and ground handling operators across the UK, EU, Middle East, Asia-Pacific, and the Americas.
