Updated: 12Sep2020 # Hydraulics Denoting, relating to, or operated by a liquid moving in a confined space under pressure. Hydraulics work on two primary principles: 1: Liquids are not compressible. 2: Pressure is equal to the force applied divided by the area it’s applied to. # Why it works... Pressure = Force/Area Example: 1 psi = 1 lbf /1 in2 100 psi = 1 lbf / .01 in2 Rearranged for Force and a constant pressure you get F=P/A. # Why it works... ![[Pasted image 20230905135455.png]] This is how your 95 pound, 16 year old daughter stops a 3000 pound car with her left foot while talking to her friends. ![[Pasted image 20230905135538.png]] This is how your wings sweep, gear drops, and flight control surfaces move with your only your right arm at Mach 1. Without hydraulics you could not rip the wings off. Using the force multiplier, coupled with being able to ‘transmit’ that pressure into an incompressible media (hydraulic fluid) allows engineers to design systems that are within a human's ability to manipulate and have that action replicated on a much larger scale well away from the operator without steel rods, pulleys, cables, etc. # Hydraulic System The F-14 has two separate hydraulic systems, the flight hydraulic system and the combined hydraulic system. Both systems are driven by hydraulic pumps connected to each engine, the flight hydraulic system from the right engine and the combined hydraulic system from the left engine. Both systems are pressurized to around 3,000 psi when operating normally. Flight control surfaces are supplied by both systems while the combined system also supplies pressure to secondary systems such as the flaps, landing gear and the refueling probe. This is so that both systems can drive the control surfaces independently from each other in case of a failure in the other. Additionally, the hydraulic systems related to systems not necessary while airborne can be isolated by a switch next to the landing gear handle. This is so that damage to those systems won’t affect the combined system pressure and cause fluid loss. The systems that can be isolated are the landing gear, wheel brakes and refueling probe. This switch is mechanically locked to not isolating these systems by the landing gear handle when it’s in the down position. If only one of the hydraulic pumps fail it’s possible to pressurize that system from the other pump via the hydraulic transfer pump. This pump is an omni-directional hydraulically driven pump that can supply either system from the other and will maintain a pressure between 2,400 and 2,600 psi if the driving system is at around 3,000 psi. If one system pressure falls below 500 psi the pump will be secured to prevent pump damage and preserve pressure in the working system. The pump can also be manually disengaged by the pilot. In case of failure of both hydraulic pumps the flight hydraulic system can be driven by an electrical pump, called the emergency flight hydraulic pump. This pump is capable of independently driving the tail control surfaces, enabling the aircraft to return home and land even without pressure in either main hydraulic system. The electric pump is automatically enabled if both main systems drop below 2,100 psi and shut off if either reaches 2,400 psi again. The automatic pump activation activates the system in the low mode but it can also manually be selected to either low or high operation. The control surfaces will have a reduced deflection rate if driven by this pump, more so in low than high. There is also a hand driven hydraulic pump that can be used to pressurize the refueling probe and wheel brake accumulator if there’s otherwise no pressure in the combined system. This is mainly for unpowered ground operation but can be used as a backup in the air. # Cockpit Orientation ![[F-14 Pilot Cockpit Panels.png]] ### Hydraulics Transfer Pump Located in back of position 11 on the diagram to the right. ### Emergency Hydraulics Located in back of position 11 on the diagram to the right. ### Emergency Parking Brake Indicator Located in bottom of position 6 on the diagram to the right. ### Hydraulic Isolation Switch Located in position 2 on the diagram to the right. ### Hydraulic Hand Pump Located in position 1 by the seat on the diagram to the right. ## HYD ISOL switch Switch isolating landing gear, nosewheel steering and wheel brakes from the combined hydraulic system. Is automatically moved to T.O./LDG by LDG GEAR in DOWN position. FLT - In flight operation, isolates systems listed above. T.O./LDG - Take-off/landing, connects systems listed above, allowing them to operate. (Not Mappable) ![[Pasted image 20230905140013.png]] ## Hydraulic Hand Pump Located between the seat and the left side console. This can be used is the hydraulic pumps fail and there is no or little damage to the hydraulic piping in the plane. Can be used for short bursts of flight control and lowering your gear. (Not Mappable) ![[Pasted image 20230905140055.png]] # Hydraulic Pressure Indicator Shows hydraulic pressure of the combined and flight hydraulic systems. SPOIL (Spoiler) ON/OFF-flag indicates pressurization of outboard spoiler module. EMER FLT HI ON/OFF-flags indicates backup flight hydraulic system pressures when HI or LOW is selected respectively. ![[Pasted image 20230905140233.png]] # Emergency Brake Pressure Displays hydraulic pressure available from the emergency brake accumulators to the auxiliary and parking wheel brake systems. **PARK** - Shows brake pressure available for parking brakes. Green segment indicates 2,150 to 3,000 psi, red indicates 1,900 to 2,150 psi. When green there is pressure enough for approximately 3 applications. **AUX** - Shows brake pressure in the auxiliary brake pressure which can be used via the toe brakes on the pedals. Green segment indicates 2,150 to 3,000 psi (approximately 13 to 14 applications) while red indicates 1,900 to 2,150 psi (approximately 5 applications). ![[Pasted image 20230905140257.png]] # Emergency Flight Hydraulics **EMER FLT HYD** - Switch controlling the emergency mode of the flight hydraulic system. Guarded to the AUTO(low) position. **HIGH** - Activates the power module (high speed mode), bypassing flight and combined 2,100 psi switches. **LOW** - Activates the backup power module bypassing flight and combined 2,100 psi switches. **AUTO(LOW)** - Automatically activates LOW mode when both flight and combined system pressures are below 2,100 psi. **(Not mappable)** ![[Pasted image 20230905140342.png]] # Hydraulic Transfer Pump Switch Panel containing the control for the hydraulic transfer pump which equalizes pressure between the combined and flight hydraulic systems in case of a failure in one of them. The HYD TRANSFER PUMP switch has two positions, SHUTOFF and NORMAL (guarded position). The NORMAL position (also the standard setting) will have the hydraulic transfer pump pressurize a failed hydraulic system from the other, functioning system, when it drops below 2,100 psi. The SHUTOFF position (which can be accessed by lifting the guard) is used to turn off the transfer pump in case it can’t supply enough pressure to the failed system as that would risk disabling the still operational system. ![[Pasted image 20230905140501.png]] # DCS Mappings... The following items are mappable in DCS under the Right Sidewall section of the pilots controls. None are recommended as immediate access is never required. ![[Pasted image 20230905140534.png]] # HYDRAULICS FAILURE >[!failure] # HYDRAULICS FAILURE CHECKLIST > - [ ] Hydraulic Isolation switch to FLT > - [ ] Verify Flight hydraulic pressure > - [ ] No Flight Hydraulic pressure? > - [ ] Verify EMER FLT Low Flag is on > - [ ] Verify control authority > - [ ] 5 min or less before landing: > - [ ] Emergency Flight Hydraulics to high > - [ ] Land Immediately > - [ ] No control authority/Low Flag off? > - [ ] Emergency Flight hydraulics to high > - [ ] Verify EMER FLT High Flag is on > - [ ] Verify control authority > - [ ] Land Immediately > - [ ] No control authority/high Flag off? > - [ ] Eject