UA28A-14

Function in the anti-skid braking system

The internal inertial mechanism responds to angular deceleration of the wheel. At the specified threshold, its contact group switches and sends a command to the electrohydraulic brake-release valve. The sensor is one element of the automatic braking loop and is not a stand-alone measuring instrument.

Within the operating loop, the UA28A-14 signal is used together with the brake-release valve, hydraulic brake circuit and aircraft wiring. False operation or absence of a command may originate in the detector, brake adjustment, wheel condition, connector or control line. Troubleshooting must therefore follow the complete circuit described in the aircraft maintenance documentation.

UA28A-14 landing-gear installation

Landing-gear documentation distinguishes the versions by installation side: UA28A-14 is assigned to the right landing-gear wheel or leg, while the related UA28A-13 is used on the opposite side. The detectors are mounted on wheel-suspension components and operate with the brakes, hydraulic lines and release valves.

Before installation, verify the direction marking, landing-gear side, mounting surfaces and connection to the rotating member. The completed installation is checked for free mechanism movement, absence of binding and reliable electrical continuity. A visually similar execution carrying another suffix must not be fitted unless the parts catalogue or an approved service instruction authorises it.

Documented aircraft application

Parts catalogues and operating manuals confirm UA27A and UA28A skid detectors in the braking systems of the Antonov An-26 and L-410; UA28A application is also documented for the An-24. The exact execution and installation side must match the parts catalogue for the individual aircraft.

Maintenance normally includes an external inspection, mounting and wiring checks and verification of the operating threshold by the approved procedure. Threshold values, permitted contact resistance and adjustment data must come from the UA28A-14 passport. Related opposite-side cards help identify system composition but do not mean that the units can be exchanged between sides.

Identification and ordering of UA28A-14

Retain the complete -14 suffix and verify the nameplate, installation side, connector and passport. Search variants UA-28A-14; UA28A 14 and УА-28А-14; УА28А 14 identify the same execution. More aircraft sensors are listed in the Aviamisto Sensors category; related products do not imply interchangeability.

An inquiry should state aircraft type and modification, installation position, left or right side, complete Part Number, condition and required documentation. If the removed unit has an incomplete nameplate, provide a photograph and the relevant illustrated-parts-catalogue reference. This allows the detector to be matched to the individual braking installation before supply.

This card identifies UA28A-14 as an individual aviation product and does not replace its passport, illustrated parts catalogue or maintenance manual. Before supply, the nameplate, condition, delivery scope, required documents and applicability to the individual aircraft or system should be agreed. When the marking, equipment record and inquiry contain different information, the approved documentation for the installed execution takes priority and any disputed parameter must be confirmed before ordering. Incoming-inspection results and traceability data should be retained with the supply documentation.

Related products are selected by common system or measured parameter. This grouping improves catalogue navigation but is not a list of approved replacements. Any substitution requires matching designation, electrical interface, mounting dimensions and range, together with explicit confirmation in the applicable maintenance documentation.