RAF Halton — Structural Steel Testing, Hangars 287 & 288

The challenge

Hangars 287 and 288 at RAF Halton are Type ‘F’ steel-framed aircraft hangars constructed around 1920 — each roughly 62 m long, 38 m wide and 15.5 m to the apex. A century after construction, the original steel’s properties could not simply be assumed: the structural reassessment needed real material data — what the steel is, how hard it is, and how much section remains. And with the hangars still in use for light aircraft and gliders, the investigation had to be planned around live operations on a defence establishment.

Our approach

Working for Clegg Associates, Infrastruct North designed a targeted structural steel investigation agreed with the structural engineer: XRF/PMI alloy screening, portable hardness testing and ultrasonic thickness surveys across roof and wall bracing, stanchion trusses, side trestles, door-frame members and connection plates, with a small number of engineer-approved coupon samples for laboratory analysis.

Fieldwork was organised in test clusters, with each cluster’s results reviewed and approved with the engineer before the team moved on. Testing at height was delivered by MEWP with exclusion zones and banksman control, and all XRF work ran under Infrastruct North’s HSE IRR17 registration with Radiation Protection Adviser oversight, temporary controlled areas and authorised operators — all inside the site’s security, photography and access controls.

The outcome

The programme delivered a complete field dataset for both hangars: alloy composition screening across the principal member types, hardness values providing indicative strength, residual thickness measurements on corroded sections, and engineer-approved coupon samples taken for laboratory confirmation of material properties.

Because every cluster was signed off with the structural engineer as the data emerged, the finished dataset maps directly onto the reassessment — measured values in place of century-old assumptions, from a programme that never interrupted the hangars’ day-to-day operations.

Why it matters

Ageing defence and industrial estates are full of steelwork that predates modern records. Reassessing these structures on real material data — rather than conservative assumption — is often the difference between targeted repair and wholesale replacement. This project shows the model: minimum-intervention, engineer-led, and delivered without disrupting a working site.