UI3-9

Oil and fuel pressure indication through UI3-9

Two channels of the UI3-9 work as pressure indicators. The oil pressure channel is used with an inductive pressure transmitter matched to the oil pressure range. The fuel pressure channel works with a higher-range pressure transmitter installed in the fuel system. In both cases, the indicator receives an electrical signal from the remote transmitter and moves the corresponding pointer on the scale. If the reading is unstable or absent, the fault may be in the indicator, transmitter, connector, wiring, AC supply or grounding. The full measuring circuit should be checked before replacing the instrument.

UI3-9 oil temperature channel and related receivers

The third channel of the UI3-9 is used for oil temperature indication. This channel works with resistance-type temperature receivers such as P-1 or P-63, depending on the aircraft documentation. The temperature circuit is normally powered from the aircraft DC network and operates separately from the pressure channels. In service, oil temperature indication is used together with pressure readings to assess engine operating condition, lubrication performance and possible abnormal heating. A wrong temperature reading can come from the receiver, bridge circuit, wiring, connector or the indicator itself.

Aircraft and equipment application of UI3-9

UI3-9 is used on aircraft and some special ground equipment of Soviet and Russian design. Typical aircraft applications include Yak-18T, Yak-52, An-2 in some modifications and repair configurations, Mi-2, Mi-8 and Ka-26. The indicator may also be found on special vehicles, airfield power units and diesel generator sets using converted aviation or heavy-duty engines. Installation depends on the panel layout, engine type, sensor set and repair history. A visually similar UI3-series instrument is not automatically interchangeable if the scale ranges or connected transmitters differ.

Connected sensors and power circuits around UI3-9

The UI3-9 normally works with ID, IDT or IMD series inductive pressure transmitters. For the oil pressure channel, the transmitter is selected for the lower pressure range. For the fuel pressure channel, the transmitter is selected for the higher fuel pressure range. The oil temperature channel is connected to a P-1 or P-63 temperature receiver. The pressure channels require aircraft AC supply, often from onboard converters or step-down transformers, while the temperature circuit uses DC power. This mixed supply arrangement is why wiring diagrams matter during installation and troubleshooting.

Identification and ordering of UI3-9

Before ordering UI3-9, the marking on the instrument should be compared with the aircraft parts catalog, cockpit panel layout and wiring diagram. The main points to confirm are scale ranges, connected transmitter types, temperature receiver type and power supply arrangement. If the instrument is being selected for an aircraft after overhaul or for special ground equipment, a photo of the installed unit and the sensor list is useful. The product is also known under alternative designations UI3-9, UI-3-9 and УИ3-9.

Related instruments: UI3-3K, UI3-6K, UR-117M. These links are grouped by function and system context and do not indicate interchangeability.