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Modifying & Repairing Aircraft

One of the main features of the LAA system is that modifications and repairs can be approved with significantly reduced costs compared with aircraft on Certificates of Airworthiness, where applicants would need to deal with the CAA or EASA.

Since the engineering team are all ‘little aircraft’ experts, it is usually a straight-forward job to approve many types of change.  Of course, with many of our members being so creative, sometimes the job takes a little more time and thought to approve!
Modifcation Type
Further Details
Application Form
Application Fee
Category Changes
Applications to change an aircraft’s category from a microlight to a ‘Group A’ aircraft (and vice versa) are allocated a modification number to record the change. If an engine or propeller change is required at the same time, then an application must be made as noted above.
Engine & Propeller Changes
These are treated as Prototype or Repeat modifications, unless they appear on the PTL list for the type.
Technical Leaflet TL 3.02
* See below
Avionics Installations
These are not considered modifications, but in order to fulfil their legal obligations, owners are required to keep LAA up-to-date should radio details alter. A special system exists for the approval of radio changes that is separate from other modifications.
Technical Leaflet TL 3.03
No charge for radio/transponder installations, but a £30 fee is chargeable for certified ADS-B Out applications
Where a change has previously been approved by means of a Supplemental Type Certificate (STC), LAA Engineering then only needs to investigate any installation/compatibility issues rather than the change itself.
The Trivial Change
Sometimes a change is so trivial that no application is required and there is no need to inform the Engineering department.
Technical Leaflet TL 3.10
Manufacturers' Modifications
Kit manufacturers and plans suppliers often have long lists of optional modifications that can be fitted and during the lifetime of a type product improvements are introduced. Generally, LAA-accepted optional items are listed on the TADS for the type.
The Standard Modification
This is a modification that is very well defined and is applicable to a particular aircraft or engine type or types. Members may nominate new Standard Modifications using form LAA/MOD 9; however, LAA Engineering may choose to convert popular Repeat modifications into Standard Modifications.
Technical Leaflet TL 3.06
Variable, see individual mods for details
The Repeat Modification
A modification that has already been approved on one aircraft as a Prototype modification. Note that a Repeat modification must identically replicate the original Prototype modification including fasteners and positions of parts and should generally be on the same aircraft type as the original.
Technical Leaflet TL 3.07 and TL 3.17
* See below
The Prototype ("normal") Modification
This is a normal modification application made in the usual way and is applicable only to the aircraft for which the application is made.
Technical Leaflet TL 3.01
* See below

* All prototype modifications (including engine and propeller changes) attract a minimum fee of £60 which covers up to two hours' work; all repeat modifications (including engine and propeller changes) attract a minimum fee of £30 which covers up to one hour's work. Thereafter, work is charged at £30/hour in either case. See the relevant Technical Leaflet for the type of modification for further details.

To access the Technical Leaflets, MOD forms and Standard Modifications described above, click one of the buttons below:

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