The sustainment layer - hangars and repair lines that maintain, overhaul and life-extend aircraft, engines and components once they're already flying.
Why it matters
MRO is the recurring-revenue counterpart to the one-time manufacturing value chain - every aircraft and engine built upstream eventually flows back through this layer repeatedly over its service life.
Where the value pool sits
MRO providers earn long-dated, recurring service revenue tied to fleet size and flying hours, rather than the lumpy, programme-driven revenue typical of component manufacturing.
Key drivers
Growing domestic commercial aircraft fleet requiring more scheduled maintenance
Government push to repatriate MRO work currently sent overseas
Military fleet sustainment and engine-overhaul cycles
Potential bottlenecks
Limited third-party civil MRO hangar capacity in India relative to fleet size
Heavy reliance on a single PSU (HAL) for most listed military MRO exposure
Long lead times and certification requirements to stand up new MRO capacity
Investor metrics to watch
ROH/MRO segment revenue growth where disclosed
New hangar/facility announcements and target completion dates