By definition an engine family creates a grouping of similar engine models for analytical purposes and to identify engine models that share design origin. The engine family is derived by combining the original engine make and original engine model or derivative of the original engine model commonly used as an engine grouping.
Initially the aircraft engine family was derived by combining the original engine make and original model name, which is equivalent to the derivation rule of the aircraft master model. Data users remarked that some aircraft engine manufacturers have established designations similar to the aircraft engine family. Data users noted that Pratt and Whitney uses the term PRATT AND WHITNET-PW4000 to group Pratt and Whitney engines with the prefix "PW4" (for example, PRATT AND WHITNEY-PW4050, PRATT AND WHITNEY-PW4052, and PRATT AND WHITNEY-PW4056). To permit the use of "aircraft family like groupings" in use by the aviation industry, an aircraft engine family can be a "derived by combining the original engine make and… derivative of the original engine model commonly used as an engine grouping" in addition to combining the original engine make and original model name.
- A national military or armed force has aircraft engines that are based on civilian models. Persons who analyze aircraft safety data may wish to review reports of military and non-military operations of the engine family. In addition, over time former military aircraft engines enter civilian aircraft registries and accident/incident databases. For example the engine family ALLISON-250 applies to the civilian ALLISON-250 as well as the military version ALLISON-T63.
- An aircraft engine manufacturer may build an aircraft engine under license to another manufacturer. An aircraft engine built under license would maintain the family name used by the manufacturer that holds the design rights. For example, the family name GLUSHENKOV-TVD10 applies to aircraft engines built by GLUSHENKOV and PZL RZESZOW.
| AIRCRAFT ENGINE FAMILY NAME |
AIRCRAFT ENGINE MANUFACTURER |
AIRCRAFT ENGINE MODEL |
| GLUSHENKOV-TVD10 |
GLUSHENKOV |
GLUSHENKOV-TVD10 |
| GLUSHENKOV-TVD10 |
PZL RZESZOW |
PZL RZWSZOW-TWD10 |
| ALLISON-250 |
ALLISON |
ALLISON-250 |
| ALLISON-250 |
ALLISON |
ALLISON-T63 |
An engine sub model is an engine manufactures designation to identify differences within an engine model grouping. An engine sub model usually reflects the lowest level description of an engine without identifying that engine. (Example the CONTINENTAL-O300-D cannot be described at a lower level without uniquely identifying that engine.)
| AIRCRAFT ENGINE MAKE |
AIRCRAFT ENGINE MODEL |
AIRCRAFT ENGINE SUB MODEL |
| CFM |
CFM56 5A |
1F |
| CFM |
CFM56 5A |
3 |
| CFM |
CFM56 5A |
4 |
| CFM |
CFM56 5A |
4F |
| CFM |
CFM56 5A |
5 |
| CFM |
CFM56 5A |
5F |
An aircraft engine manufacturer is the organisation that actually builds an aircraft engine at the time of completion. The valid values refer to an organisation when referencing the aircraft engine manufacturer. By definition, the aircraft engine make is the name assigned to the aircraft engine by the manufacturer when each engine was produced. In most cases aircraft engine make is the same as aircraft engine manufacturer. As an example Continental, an aircraft engine manufacturer, builds the aircraft engine model O200 (CONTINENTAL-O200). Rolls Royce under license built CONTINENTAL-O200 aircraft engines. The table below lists the two manufacturers of the CONTINENTAL-O200. In this case Rolls Royce built engines that were referenced as the CONTINENTAL.
| MANUFACTURER NAME |
AIRCRAFT ENGINE MAKE |
AIRCRAFT ENGINE MODEL |
| CONTINENTAL |
CONTINENTAL |
O200 |
| ROLLS ROYCE |
CONTINENTAL |
O200 |
Yes. This is common when one manufacturer purchases another manufacturer. The purchasing manufacturer may continue to use the earlier aircraft engine make. In the example below Rolls Royce purchased Allison. Rolls Royce continued to use the "Allison" aircraft engine make for engines previously built by Allison.
| MANUFACTURER NAME |
AIRCRAFT ENGINE MAKE |
AIRCRAFT ENGINE MODEL |
| ROLLS ROYCE |
ROLLS ROYCE |
SPEY511 |
| ROLLS ROYCE |
ALLISON |
250 |
Yes. An example is when a particular aircraft engine is built by more than one aircraft engine manufacturer. Pratt and Whitney as well as Pratt and Whitney Canada use the make PRATT AND WHITNEY.
When reviewing draft valid values the sub-team perceived the need to differentiate whether a reference to PRATT AND WHITNEY-PW4090 is either
- A grouping of all aircraft engines with the same aircraft engine model (for example, PRATT AND WHITNEY-PW4090-3 or PRATT AND WHITNEY-PW4090-D)
- The aircraft engine designator for a PRATT AND WHITNEY-PW4090 aircraft engine model without a sub model.
To alleviate this issue, the sub team created the term "Undesignated Sub Model" for aircraft engines where one sub model of an aircraft engine model, typically the earliest one, is known by the engine model designation (for example, PRATT AND WHITNEY-PW4090). By creating the term "Undesignated Sub Model" the earliest version is described as an PRATT AND WHITNEY-PW4090-UNDESIGNATED SUB MODEL.
| AIRCRAFT ENGINE MAKE |
AIRCRAFT ENGINE MODEL |
AIRCRAFT ENGINE SUBMODEL |
| PRATT AND WHITNEY |
PW4090 |
UNDESIGNATED SUB MODEL |
| PRATT AND WHITNEY |
PW4090 |
3 |
| PRATT AND WHITNEY |
PW4090 |
D |
When reviewing draft valid values the sub team noted that in some instances an aircraft engine cannot be described at a level lower than aircraft engine model. To ensure that users know that the aircraft engine model level is the lowest, the sub team created the term "No Sub Model Exists." Therefore a LYCOMING-AL5512-NO SUB MODEL EXISTS clarifies that the aircraft engine cannot be described any lower than aircraft engine model level.
| AIRCRAFT ENGINE MAKE |
AIRCRAFT ENGINE MODEL |
AIRCRAFT ENGINE SUBMODEL |
| LYCOMING |
AL5512 |
NO SUB MODEL EXISTS |
