Historically, the flight deck cabin doors on commercial aircraft were simply intended to provide privacy for the pilots and on many smaller regional aircraft curtains were used for this purpose. Apart from the obvious need to ensure that the crew could escape in emergency there were very few FAA (US Federal Aviation Administration) regulations applicable to the doors.
With high-flying commercial aircraft being pressurized for passenger comfort, a rapid decompression event, such as a windshield failure can result in a large pressure difference between the main cabin and flight deck. This in turn would cause catastrophic structural damage, such as buckling of the bulkhead (the nose/cockpit section). To prevent this from happening all aircraft use some kind of a vent or valve to rapidly equalize the pressure before this dangerous threshold is reached. In most cases this vent or valve feature is provided within the design of the cockpit cabin door. In this case during a decompression event the doors pop open to equalize the pressure between the cockpit and cabin before structural damage can occur.
Consequently the latches that secure the doors must be able to release at a low pressure differential. However, this means that they can be easily overcome by an unwanted intruder.
Post September 11th , flight deck doors are now seen as front line security and new security measures introduced by the FAA require that the cockpit door latches must also become extremely resistant to forceful intrusion. New regulations, which take effect in April 2003, demand that these doors resist impacts of 300 joules and small arms fire. In other words no-one is going to get past them! However such stringent levels of security must also allow for the rapid equalization of any pressure differential.
Hartwell Corporation has risen to this extremely demanding challenge through the rapid development of an innovative latching mechanism for flight deck doors that exceeds the regulatory requirements and is gaining acceptance by major cockpit door manufacturers and aircraft companies.
The latch beats all safety requirements of:
- pressure relief - releasing before pressure differential builds to dangerous levels, and
- intrusion resistance - impervious to impacts of 300 joules.
…thus giving all who fly comfort in their security and safety, thanks to Hartwell’s engineers.
This is another example of “Collaborative Solutioneering @ pace” from the Hartwell Corporation. Having received the first order for these latches in April, they will be fitted to single aisle Boeing aircraft in the very near future.
