Aircraft Skin-Penetrating Nozzle Testing of a Freighter Aircraft Cargo Liner

Following the in-flight cargo fire accident involving United Parcel Service (UPS) flight 1307 at the Philadelphia International Airport on February 7, 2006, the National Transportation Safety Board determined that the Aircraft Rescue and Firefighting personnel did not have adequate training in fighting freighter aircraft fires. A post-incident, on-aircraft analysis by UPS personnel suggested the cargo liner interfered with the aircraft skin-penetrating nozzle’s (e’s (ASPN) ability to discharge firefighting agent on the fire. The UPS analysis suggested that the firefighting agent became trapped between the cargo liner and the fuselage, implying that the liner separated from the fuselage and acted as a shield, which prohibited the firefighting agent from controlling the cargo fire. The research described in this report evaluates the role of cargo liner in penetration of an aircraft with an ASPN.

Small-scale scoping tests identified the penetration behavior of heated cargo liner within an area of approximately 480 square inches. The cargo liner was mounted in a frame and penetrated with an ASPN that was fitted to a hydraulic ram. Initial penetration tests were conducted with cargo liner intact. Heated tests involved penetration while the material was directly exposed to a kerosene burner flame. Full-scale tests examined the role of cargo liner mounting hardware in ASPN penetration. The full-scale test article was composed of a mockup section of the freighter aircraft. This was created by mounting the cargo liner in a section of a modified C-133 aircraft. A cargo liner mounting frame was duplicated from an example freighter aircraft. The frame used normal aircraft construction techniques and materials. Electric radiant heaters and liquid fuel pool fires served as heat sources. An ASPN mounted on a high-reach extendable turret (HRET) was used to penetrate the aircraft.

Penetration results were evaluated based on the number of unblocked ASPN holes on the interior side of the cargo liner. Under ambient conditions, the cargo liner did not significantly stretch or otherwise impede penetration. The heated cargo liner exhibited limited stretching or sagging, but not enough to obstruct the ASPN. Only 1 of the 45 full-scale heated tests demonstrated significant nozzle obstruction. Small-scale heated tests indicated that incomplete penetration or reduced penetration depth could lead to obstruction of 33% to 77% of the nozzle. Overall, tests indicated that cargo liner material does not normally hinder the use of an ASPN for application of firefighting agent. Given sufficient penetration length, it was observed that the ASPN is capable of penetrating through the cargo liner into the interior of the aircraft.

DOT/FAA/TC-12/48

Author: William Doig