Cabin Pressure Bulkhead Frames

Cabin pressure bulkhead frames are key structural interfaces that withstand significant pressure differentials between the pressurized cabin and unpressurized fuselage sections. They transfer hoop, shear, and axial loads to surrounding structures while maintaining structural integrity.

Material Specification

Aluminum 2024-T351 (AMS 4037), 7075-T7351 (AMS 4050)

Profile Geometry

“Z” or “J” Section, Circumferential Frame with Doublers, CAD-Matched to Fuselage Contour (±1mm)

Thickness

Web – 2.0-6.5mm, Flange – 3.0-8.0mm (Tapered for weight optimization)

Pressure Differential Capacity

8.6-9.5 psi (FAR 25.841 Compliant), Burst Pressure ≥1.5x Operating

Load Capacity

1.5mm – 25mm (Adjustable nut/lockwasher for varying thicknesses)

Product Description

Engineered to endure cyclic pressurization loads exceeding 8 psi, these cabin pressure bulkhead frames are designed to meet strict damage tolerance criteria for Class I structural components. Their profiles ensure consistent load transfer without distortion, supporting long-term airframe durability under repeated pressurization cycles.

Deflection Limits

≤3mm Deflection @ Max Pressure, Natural Frequency >60 Hz

Fatigue Life

50,000 Pressurization Cycles (2x Service Life), Validated per ASTM E606

Corrosion Resistance

Alodine 1200 (Aluminum), Epoxy Primer (CFRP), Sealed Joints (PRC/PS870)

Dimensional Tolerances

Hole Position – ±0.15mm, Profile Contour – ±0.5mm, Flatness – ≤1mm/m

Certification Standards

FAR 25.365/571, AITM 2-0006, BMS 7-260, AS9100

Technical Advantages

Airframes experience thousands of pressure cycles throughout their service life, leading to material fatigue in regions with high stress concentrations. The bulkhead frame’s geometry incorporates fillet radii, smooth load paths, and cold-worked fastener holes to mitigate crack initiation. Fracture mechanics-based analysis informs the frame’s wall thickness and profile transitions to ensure fatigue crack growth rates remain within acceptable limits during worst-case mission profiles.

Cabin pressure bulkhead frames are integrated with fuselage sections, requiring exacting flatness, perpendicularity, and hole positional tolerances. Tolerance stacking across the circumferential interface is minimized using CNC-machined contours with positional tolerances as tight as ±0.05 mm. This level of control ensures that frame-to-skin joints and fastener alignments are achieved without inducing residual stress or requiring post-fit modifications during airframe assembly.

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Industry Applications

Fuselage Pressure Boundary Termination

Provides structural closure for pressurized cabin zones, maintaining airtight separation from unpressurized fuselage compartments during all flight phases.

Load Path Reinforcement in Mid-Fuselage Sections

Transfers axial, hoop, and shear loads from pressurized structures to surrounding fuselage frames, ensuring stress distribution under cabin pressurization.

Integration of Environmental Control System Passages

Accommodates ECS duct interfaces through machined provisions, enabling sealed and structurally supported routing of conditioned air between compartments.

Interface Structure for Aft Pressure Dome Assemblies

Serves as mounting and sealing interface for aft pressure domes, enabling differential pressure containment across rear fuselage cross-section.

Support Structure for Rear Avionics or Cargo Bays

Acts as structural barrier between pressurized passenger cabin and unpressurized avionics or cargo zones in civil and military aircraft.

Structural Anchor for Interior Cabin Installations

Provides stable interface points for interior components like flooring beams and bulkhead partitions subjected to fluctuating cabin pressure loads.

Alloy Selection for Dual Requirements of Strength and Corrosion Resistance

Selection of aerospace-grade materials, such as 7050-T7451 or Ti-6Al-4V, balances the competing needs of strength-to-weight optimization and corrosion resistance in high-humidity pressurized environments. Heat treatment processes are tightly controlled to achieve specified mechanical properties, including yield strength exceeding 70 ksi for aluminum frames.

Surface preparation and finishing are configured to ensure chemical compatibility with fuselage sealants and structural adhesives. Chromate conversion coatings or Type I/II anodizing are applied to maintain corrosion resistance without compromising adhesive bond strength.

Having Doubts? Our FAQ

Check all our Frequently Asked Question

How does Frigate ensure dimensional stability of cabin pressure bulkhead Frames during long machining cycles?

Frigate uses low-stress forged or rolled plate stock with uniform grain orientation to reduce warping during material removal. Fixtures are thermally stabilized, and CNC paths are optimized to balance material removal rates across the structure. In-process probing verifies critical dimensions before part release. Final inspection includes 3D scanning against CAD to detect profile deviations.

What material traceability systems does Frigate use for pressure cabin pressure bulkhead frames production?

Frigate assigns a unique serial number to each frame, linked to the parent material heat lot and supplier batch. All materials conform to AMS or OEM specifications and are validated with MTRs from NADCAP-approved labs. Material movements are logged through ERP-integrated digital tracking. Full traceability is maintained for over 15 years as per aerospace documentation standards.

How does Frigate address fatigue-critical areas in the pressure bulkhead design?

High-stress regions such as flange transitions and fastener lines are analyzed using FEA with variable amplitude pressure cycles. Frigate applies cold working or shot peening to selected features to extend fatigue life. Geometry is refined using crack propagation modeling to comply with OEM damage tolerance criteria. Coupon testing and full-scale mockups are used for fatigue validation.

What surface treatment options does Frigate offer for corrosion protection in moist pressurized environments?

Frigate offers Type II sulfuric acid anodizing, chromate conversion coatings, and primer-compatible sealing systems per MIL-DTL-5541 and AMS2471. Treatments are selected based on galvanic compatibility with adjacent fuselage alloys and fasteners. Coated samples undergo salt spray and humidity exposure tests. Application is performed in-house under strict environmental controls and NADCAP accreditation.

How does Frigate support integration of ECS and structural systems into cabin pressure bulkhead frames?

Frigate machines, ducts, penetrations, and mounting features per OEM interface control documents (ICDs). Reinforcement strategies like flanged openings and bonded doublers are integrated into the machining process. Tolerances for connector alignment and seal interfaces are verified using CMM and GD&T protocols. All features are documented in 3D models and included in delivery reports.

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