Altitude (vacuum, pressure) -

Sometimes product developers don't properly consider the pressure sensitivity of off-the-shelf subsystems or internal components when reviewing various environmental requirements.

Examples of Altitude caused product failures:

• 'Pressure cycle induced fatigue' - fittings of mechanical components in a product weakened and eventually failed when exposed to unusual cyclical pressure changes. [This could also be in the 'Fatigue' category.]
• Sensors and activators inside a sub-assembly rely on a specific pressure differential between the inside of the product housing and the external environment for proper operation of the product. The product failed when used in a private plane at 15,000 feet altitude.
• Some precision mechanical devices (e.g., disk drives, pumps, etc.) have pressure sensitive lubrication seals that do not maintain proper lubrication when operating outside a specific ambient pressure range.
• Portable pressure systems can unintentionally be used at altitudes for which they are not designed.