Aircraft component reliability is a significant underlying contributing factor for dispatch reliability as well as aircraft systems reliability. Afterall, it are the individual parts and components that make up an aircraft. Having adequate and meaningful insight into the individual reliability of components can greatly assist in identifying any potential reliability improvement actions and subsequently improve aircraft / fleet availability. How can Heads of Engineering gain meaningful understanding in the reliability of components installed in the aircraft? 

Reliability of individual aircraft components is being determined by the total time each component is installed on an aircraft prior to it being removed. Removal of an aircraft component can be triggered by either a scheduled maintenance action being required on the part or due to an unexpected failure of the component requiring it to be replaced.

Within aviation each part installed on an aircraft is defined by a part number and a serial number. A part number is a reference to a generic part (i.a. 0851HT1 is a part number for a PITOT PROBE. Whereas a serial number is a reference to an individual unit/component within that part number (i.a. 23049). As such a full component identification would be 0851HT1 – sn: 23049. The main reason for identifying individual serial numbers within parts is to allow the tracking of flying hours / cycles accumulation on individual units for maintenance requirements purposes. As such the important metrics that are being tracked on individual components include:

Time Since New (TSN)

The total amount of flying hours accumulated on a serialized component since its production.

Cycles Since New (CSN)  The total amount of cycles accumulated on a serialized component since its production
Time Since Installation (TSI) The total amount of flying hours accumulated on a serialized component since it was installed on the aircraft it is currently installed on.
Cycles Since Installation (CSI) The total amount of cycles accumulated on a serialized component since it was installed on the aircraft it is currently installed on
Time Since Overhaul (TSO) The total amount of flying hours accumulated on a serialized component after it was overhauled in a repair shop
Cycles Since Overhaul (CSO) The total amount of cycles accumulated on a serialized component after it was overhauled in a repair shop
Mean Time Between Unit Removal (MTBUR) The average time flown (in hours, cycles) between moment of installation of the part and removal of a generic part

Each part manufactured for an aircraft comes with an expected MTBUR. This is often used by manufactures to guarantee a certain live of each component on an aircraft once installed. The rational here being that the longer a part can remain on an aircraft the less maintenance downtime can be expected, lower maintenance costs are associated with the part and subsequently the higher the aircraft availability will be.

From that perspective airlines keep track of the specific MTBUR of individual installed components in order to identify if the installed parts meet the specifications as laid down by the manufacturer of the parts. A lower than expected MTBUR can point to either a faulty design, material issues or inadequate maintenance practices.

Within Avilytics, unscheduled component removals analyser allows to identify those components that are removed unscheduled with the highest frequency and/or with deviating behaviour from other parts in the fleet.

Unscheduled removals avilytics

 

 

 

 

 

 

 

 

For each individual component it also provides further detailed data into the removal events itself, thereby allowing airlines to validate actual component MTBUR with documented MTBUR from component manufacturers.

Additionally, the unscheduled component removal analyser calculated an anticipated number of days of installation for any part number. By making use of historical available Times Between Installation and the average projected aircraft utilization, the system can provide an expected live duration of each component.

How can the removal of parts and their individual tracked hours & cycles be adequately tracked?

Keeping track of serialized parts installed on an aircraft (configuration status) is a main regulatory requirement for airworthiness management. Today many MRO software provide the ability to keep track of the serialized components installed on an aircraft. In addition, each airline needs to have a process defined in which it keeps track of parts removals and installations. In addition, a part removal and installation are maintenance actions, which require recording of the maintenance action in the Aircraft Technical Logbook.

Tip:        Keeping track of component assemblies and positions will assist in targeted technical investigations for component reliability

Many components installed on an aircraft fit to a larger component assembly, i.e. a brake is part of the wheel assembly, and on its turn a wheel assembly is part of the broader landing gear. Keeping track of the assembly structure on each aircraft helps in identifying any potential reliability issues within specific configurations of parts and serial numbers. Additionally, keeping track of the position codes each part is installed on, will allow to spot trends that might relate to impaired component reliability dependent on the position a part is installed on.

Do you have any questions?

Feel free to contact us or give us a call on +31 20 8200 7600. We would be happy to help you further. 

What is AVILYTICS?

AVILYTICS is a fully out-of-the-box aircraft reliability management solution that focuses on providing insights in technical reliability, upcoming potential technical failures as well as organizational efficiency analytics. It combines the traditional scope of aircraft and fleet reliability management with advanced techniques from predictive analytics to also build AOG risk profiles of aircraft, identify aircraft based reoccurring defects and measure organization performance. A full holistic approach to using data in order to increase aircraft availability and fleet performance.