When it comes to aerospace hydraulic systems, using the right type of fitting is critical to safety, performance, and system reliability. A common question in the industry is: Can JIC fittings be used instead of AN fittings?

While JIC (Joint Industry Council) and AN (Army-Navy) fittings look similar and are sometimes used interchangeably in conversation, they are not the same—and using them incorrectly can lead to leaks, damage, or even complete system failure.

In this article, we’ll break down the key differences between AN and JIC fittings and explain why AN fittings are essential for aerospace applications.

What Are JIC fittings?

JIC fittings are manufactured to SAE J514 standards and use 2A/2B UNF thread classes. These threads have a standard root design and are commonly used in:

• Industrial hydraulic systems
• General fluid transfer systems
• Equipment that operates under moderate pressure and temperature

JIC fittings are cost-effective and easier to manufacture, making them a popular choice in non-critical applications where extreme reliability is not required.

What are AN fittings?

AN fittings, short for Army-Navy fittings, were developed to meet stringent military and aerospace specifications. They are manufactured to:

• 3A/3B UNJ/UNJF thread classes, which have tighter tolerances
• A larger, more controlled root radius, which enhances fatigue resistance
• Higher standards for pressure, vibration, and temperature resilience

These fittings are used in high-performance, mission-critical applications, including:

• Aerospace hydraulic systems
• Military-grade equipment
• Aviation fuel and brake lines

AN fittings are engineered for high stress, long life, and maximum safety.

Can you mix JIC and AN fittings?

Technically, JIC and AN fittings share the same:

• Thread size
• 37° flare seat angle

Because of this, they may appear to be compatible and may even thread together. However, using them interchangeably is a critical mistake for the following reasons:

1. Thread design differences

• JIC threads have a sharper root, which can damage the mating AN threads
• This damage can compromise the thread integrity, leading to cracks or failures

2. Risk of leaks

• Mismatched thread forms and tolerances may prevent a proper seal
• This increases the likelihood of leaks, especially under high pressure

3. System failure in aerospace applications

• In aerospace, a minor leak or crack can result in serious safety hazards
• Always using AN fittings ensures compliance with aerospace safety standards

Why AN fittings are the right choice for aerospace

To sum it up, AN fittings are purpose-built for high-reliability aerospace and military applications. They provide:

• Superior durability
• Enhanced safety
• Longer operational life
• Tighter manufacturing tolerances

On the other hand, JIC fittings are better suited for industrial and general-purpose systems where extreme conditions aren’t present.

Final verdict: Never substitute JIC for AN in aerospace

Even though JIC and AN fittings may look alike and physically fit together, they are not interchangeable. For any system involving aerospace-grade hydraulic lines, fuel systems, or pressurized fluid transfer, always use AN fittings.

✅ Use AN fittings for aerospace.

❌ Avoid using JIC fittings in critical applications.

For additional details about Aerocom Specialty Fittings’ Aerospace fittings, please visit our website page. Aerocom’s technical sales team members are also available to answer any of your questions. Reach out to us today!