New Delhi, April 10 -- Trouble for Air India Ltd. is mounting with aircraft technicians planning a strike later this month after its pilots voiced concerns last week about being overworked and underpaid.

Technicians at AI Engineering Services Ltd. "- a state-run maintenance, repair and overhaul firm and an erstwhile Air India unit "- will strike on April 23 due to various issues affecting their "well-being" and "professional growth," All India Aircraft Maintenance Engineering Union wrote in a letter dated April 8 to the chief executive officer.

The unrest among aviation workers risks thwarting India's air travel boom. Pilots and aircraft engineers are crucial to support the country's rapid fleet expansion after IndiGo, Air India and Aka...