What Are Tear Straps? The hidden feature of fuselage construction
- Craig Reid
- Nov 4, 2025
- 2 min read
Tear straps are reinforcing bands built into the fuselage skin, typically between stringers or frames. They are usually made from aluminium alloy and co-cured or bonded during fuselage assembly. Their main purpose is to arrest a propagating crack caused by fatigue or impact damage — stopping it from spreading across multiple fuselage bays and preventing catastrophic decompression.
How They Work
When the pressurised fuselage develops a skin crack:
The crack runs until it reaches a tear strap.
The strap redistributes stress loads and acts as a barrier.
The crack’s energy dissipates, halting its growth.
The aircraft remains structurally safe, giving time for maintenance repair.
On the 737, these are positioned longitudinally along the crown and side skins, between circumferential frames, particularly in the lap joint regions where fatigue is more likely.
Tear Straps Design & Material
Material: Same or slightly thicker aluminium alloy (e.g., 2024-T3)
Attachment: Integral to the skin panel or bonded with high-strength adhesive
Spacing: Optimised based on pressurisation cycles, typically every 15–20 inches
Inspection: Checked visually or by eddy current during C- or D-checks
737 Case Study
After incidents like the Aloha Airlines 737-200 fuselage rupture (1988), Boeing enhanced fuselage structural design:
Improved lap joint bonding
Added tear straps and doublers in key locations
Updated inspection programs under the Boeing Structural Repair Manual (SRM)
Modern NG and MAX models have integral tear straps as part of the skin panel manufacturing process, improving fatigue resistance and damage tolerance.
Jotore Aviation Insight
Tear straps are a quiet hero of aircraft safety — invisible to passengers but vital to every flight’s pressurisation cycle. Their clever simplicity embodies the engineering philosophy: “design for damage tolerance.”
Stay Safe
Craig
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