Engine air particle separator for use with gas turbine engine

An engine air particle separator adapted to be connected to the inlet of a gas turbine engine to control air flow thereto and comprising:

• (A) first flow path defining means connecting the engine inlet to atmosphere and fabricated to separate foreign particles from the air passing therethrough to the engine,
• (B) second flow path defining means connecting the engine inlet directly to atmosphere therethrough and oriented so that ram air may be directed therethrough into said engine inlet with minimal pressure loss,
• (C) door means in said second flow path defining means actuatable between a closed position wherein air flow through the second means is blocked so that all air entering the engine must flow through the first means, and an open position wherein air flow through said second means is permitted,
• (D) pressure responsive door actuating means which is spring biased to cooperate with ram air door loading to normally retain the door means in said open position, and which is responsive to applied operating pressure to overcome the force of the spring bias and the ram air door loading to move the door means to the closed position,
• (E) means to supply operating pressure to said door actuating means to actuate said closed position and to remove operating pressure from said door actuating means to permit said door means to move to said open position, and
• (F) means to prevent said door means from moving to said open position when the actuating pressure is supplied to said actuating means from said supply means but has fallen below a predetermined pressure.