Proven Condition Monitoring Solutions

High Performance Optical Pick-up Information

The High Performance OPU has been specifically designed for permanent installation onboard aircraft and has proven performance and reliability as part of many HUMS installations.  The HPOPU complies with EMC and environmental requirements of Mil Std 810E, Def Stan 59 41, BS.3G.100 and RTCA DO160C.  It also meets the interface requirements of the Rotorcraft Industry Technology Association (RITA).

It is used to produce a speed reference signal from a rotating component for timing and indexing purposes. OPU’s have an operating range of up to 2 meters and can be used to simplify installation when the use of an MPU is not practical or safe. Helitune OPU’s have been specifically designed for aircraft installations and are ideally suited for use on helicopter tail rotors and high speed transmission shafts.

The Optical Pick-Up unit works by transmitting a beam of infra red light, which is reflected back to the unit by the passing of a target of reflective tape or paint attached to the rotating component. An electrical pulse is produced each time the target comes into view and the red LED indicator illuminates on the OPU body. This signal is used to generate a speed output and a timing reference for balance data, vibration signatures and tracking information.

Technical Specification
Sensing Speed Range
Sensing Distance
Timing resolution
Operating Temperature Range

3 to 50,000 rpm (subject to min.
target passing period of 50?s)
20 to 1000 mm for reflective tape with
25x25 mm target 75 to 200 mm for
reflective paint  with 25x25 mm target
0.25º (<6000 rpm), 7µs (<6000 rpm),
@ 120 mm with reflective paint
38,000 hours
-40º C to +70º C
Green lamp in presence of power,
Red lamp in presence of target
Def-Stan 59-41

Electrical Specification
Electrical Interface
Power Supply

MIL C 38999 Series III
One TTL compatible output. One
AS5392 (formally RITA) compatible
switch output
+10 to +30V DC, at 100mA max.
Reverse polarity protection
Compliant with Mil-Std-704C
10M ohm @ 100V (case to electronics)

Physical Specification
Helitune Part Number

56mm (Including stud) x 53 mm
(excluding mating connector) x 25 mm
85 grams, including 2 locking nuts
16 mm long stud concentric with
the sensing elements with 5/8 UNF thread
DIN 40 050 ip65

  • High Performance OPU Data Sheet

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