Praedifa Technology Division

Praedifa Technology Division - Flight Control

Flight Control

Flight Control

Flight control systems are grouped into primary and secondary flight controls. The former ensure safe and controlled flight conditions for which the aileron, rudder and elevator are responsible. The control surfaces of secondary flight controls influence the aircraft’s uplift and drag.


New technologies such as control electronics used in fly-by-wire systems ensure attitude-dependent permanent motion of the flight control systems and thus the actuators. These conditions require particularly wear-resistant sealing materials in combination with a seal geometry designed specifically for this purpose. For particularly challenging applications, so-called tandem sealing systems in the typical glands for this market according to MIL-G-5514 F or AS4716 are used.


In tandem sealing systems, two rod seals are positioned behind each other. This results in higher reliability compared to conventional sealing systems. Additionally, the secondary rod seal is able to trap the residual oil film of the primary seal.


The wear- and extrusion-optimized sealing materials from Parker Praedifa in interaction with optimized seal geometries make it possible to achieve further extensions of the sealing system’s service life and thus the maintenance intervals.


Typical application and ambient conditions for actuators in aviation (depending on type of aircraft and application):

• Service temperature: -65 °F to +300 °F / -55 °C to + 150 °C

• Service pressure: ≤ 5,000 psi / ≤ 345 bar

Typical service media are MIL-H-5606, MIL-PRF-8328 and MIL-PRF-87257.


X1 Anti-Extrusion Rings


Parker Hannifin GmbH

Engineered Materials Group
Arnold-Jäger-Str. 1
74321 Bietigheim-Bissingen
Tel. +49 7142 351-0