First SPINE-Upgraded H-1 Helicopters Enter Flight Testing Phase

Bell Textron has completed the first AH-1Z Viper and UH-1Y Venom helicopters upgraded under the US Marine Corps’ Structural and Power Improvements for NextGen Effects (SPINE) programme, marking an early milestone in the service’s ongoing H-1 fleet modernisation effort.

The two aircraft were modified at Bell’s Amarillo Assembly Centre in Texas and have since been transferred to Naval Air Station Patuxent River for flight testing. The test campaign will be used to evaluate the upgraded systems and inform the final configuration for future production and retrofit work across the wider fleet.

SPINE, formerly known as the Structural Improvement and Electrical Power Upgrade (SIEPU) programme, has been rebranded to reflect a broader scope focused on enabling future mission capabilities. The initiative centres on strengthening the aircraft structure and increasing electrical power capacity, both of which are necessary to support the integration of more advanced onboard systems.

The AH-1Z and UH-1Y helicopters form the backbone of the Marine Corps’ light attack and utility helicopter capability. As mission requirements evolve, particularly with the growing emphasis on networked operations and advanced sensors, the limitations of legacy electrical and structural systems have become more apparent. The SPINE upgrades are intended to address these constraints and extend the operational relevance of the platform.

Following completion of the modifications, the aircraft will undergo a series of ground and flight evaluations at NAS Patuxent River. These tests will assess performance, system integration and overall airworthiness, helping to determine how the upgrades will be standardised in future modification efforts. The work carried out on the first two aircraft began at Bell’s Drive Systems Centre and Repair and Overhaul Centre before moving to Amarillo for final assembly and modification. The process, which spanned approximately 19 months, involved structural reinforcements and updates to the aircraft’s electrical generation and distribution systems.

The SPINE programme is part of a broader effort by the US Marine Corps to ensure its existing rotary-wing platforms remain capable of operating alongside newer systems in a joint and multi-domain environment. Increased electrical capacity is particularly important as aircraft are required to support more sophisticated avionics, communications systems and weapons.

While Bell is the prime contractor for the upgrade work, the programme has involved coordination between the manufacturer, US government stakeholders and industry partners. The completion of the first aircraft provides a baseline for subsequent modifications, which are expected to be carried out over an extended period.

No timeline has been publicly detailed for full fleet implementation, but the programme is anticipated to continue over the next decade as additional aircraft are inducted for upgrade. The outcome of the current flight testing phase will be critical in determining the pace and scope of future work. As testing progresses, further details are expected to emerge regarding the performance of the upgraded systems and their impact on operational capability.