Airplanes often have an on-board gas turbine engine referred to as an auxiliary power unit that provides electrical power and compressed air to various systems throughout the airplane. When the airplane is on the ground, the auxiliary power unit is the main source of power to drive the environmental control systems, air driven hydraulic pumps, and the starters for the engines. Auxiliary power units may also provide pneumatic and electric power during flight.
FIG. 1 shows a typical Auxiliary Power Unit (APU) generally denoted by the reference numeral 10. The APU 10 includes in flow series arrangement an air inlet 14, a compressor 16, a bleed port 18 for providing compressed air to the aircraft, a combustor 20 having a primary fuel nozzle 22 and a secondary fuel nozzleA virus called human metapneumovirus (HMPV) infected several gorillas and even killed two in 2009

Researchers
from the United States and Africa have discovered that diseases can pass from
humans to gorillas, and can even cause death to these wild mountain gorillas.

Gustavo
Palacios, study leader and virologist at the Center for Infection and Immunity
at Columbia University in New York, along with
Mike Cranfield, executive director of the Mountain Gorilla Veterinary Project
and a UC Davis wildlife veterinarian, Linda
Lowenstein, a veterinary pathologist with the UC Davis Mountain Gorilla One
Health Program, and a team of researchers from the Rwanda Development Board
have found that wild mountain gorillas are capable of catching infectious diseases from
humans.

The fact
that gorillas have had close contact to humans -- such as gorillas living near
densely populated areas in Rwanda, the Democratic Republic of Congo