Engineering Matters

Including: Be on the lookout for engines on sale without documentation or logbooks, ignition switch wear, Auster brake plate cracked, and Van’s stick boot service letter

Welcome to Engineering Matters – the section of Light Aviation that is dedicated to discussing all manner of topics concerning both technical and operational aspects of the LAA fleet. We all learn by sharing information, so if you have anything to say that you think would benefit others, or have experienced an interesting technical issue or component failure, then please contact us with a description of what you encountered and include accompanying pictures. Send your submissions to LAA Engineering at engineering@laa.uk.com

Engines: Buyers beware…

LAA member and aircraft owner, Jan Henslow, highlighted an online advertisement to LAA Engineering which he had seen for two Rotax 912-S3 engines that were for sale.

The advert said that there were no log books and that in the seller’s opinion, they were ‘ideal for LAA (aircraft)’ and had been removed from ‘an CofA Aircraft’.

There is every chance that the sale of the engines was 100% legitimate, but it might be considered somewhat unusual that engines removed from an aircraft holding a Certificate of Airworthiness, have no log books. If both engines had actually been removed from a certified twinengined, Rotax-powered aircraft, then that narrows them down to being removed from a Tecnam P2006T.

Another LAA member called LAA Engineering to ask if a Lycoming with no history could be used in an LAA aircraft.

Again, it is somewhat unusual to have an aircraft engine with zero history, log books or documentation and not even any knowledge of the airframe that they were removed from.

There are no hard and fast rules as to whether ‘unknown’ engines, devoid of log books or history (or both) will be accepted for use in an LAA-administered aircraft.

Certainly, such an engine would need to be disassembled and inspected by an appropriate person to ascertain its condition and, as far as is possible, its provenance, but in these cases it is wise to consult with LAA Engineering before parting with any hard-earned cash.

Wear in ignition switches

CHIRP, the independent and confidential aviation reporting system, commented on the subject of worn ignition keys and ignition switches in their August 2022 issue of Aviation Feedback

The problem is well known to aircraft maintainers, but may not be as well known to aircraft owners and operators, and it is not necessarily just an issue of an old and well-used key in an old and well-used ignition switch.

Particularly in the case of syndicateowned aircraft, ignition keys get copies made and then copies are made of copies… and so on over the years. These (and old, original) keys may operate the ignition switch as advertised but it is not uncommon to find that the key can be pulled from the ignition switch in more than just the ‘OFF’ position.

Apart from periodically checking (with the engine off) that the ignition keys cannot be removed with the ignition off there is another important check that can be carried out on magneto equipped engines with the aid of a magneto synchroniser ‘buzz box’.

At the annual inspection, or whenever checking the magneto timing, try moving the key around in the switch. In the ‘OFF’ position, there should be no hint from the buzz box of the ignition system being anything but ‘OFF’ and similarly, with the switch in ‘LEFT’, ‘RIGHT’ or ‘BOTH’, ensure the ignition remains live at all times. If the buzz box lights indicate that the magnetos may be live when ‘OFF’ or earthed out (i.e. off) when they should be live, further investigation is required.

Some ignition installations require one or the other magneto to be earthed out when the starter is engaged. This is accomplished with a jumper plate fitted across two terminals on the back of the ignition switch.

The normal reasons for this is that either one of the magnetos does not have an impulse coupling to retard the ignition during engine start, or that the ignition system consists of one electronic ignition unit and one magneto and the magneto is switched off during engine start.

Service bulletins and airworthiness directives: Date of compliance

From time to time, LAA Engineering receive enquiries regarding the compliance interval for Service Bulletins (SB), Airworthiness Directives (AD) and CAA Mandatory Permit Directives (MPD).

The first point to make is that compliance with an SB is not ‘legally’ mandatory, regardless of the statement made on the document itself. An SB will be mandatory if made so by the issuance of an AD or MPD.

For an AD/MPD, which has a calendar-based repetitive compliance period, the next required compliance date will be the date the AD/MPD compliance was signed up in the logbook, plus the stated compliance period (there may be allowance to add).

As an example: If an AD required a 12 month repetitive inspection and was signed in the logbook as being carried out on 12 July 2022, it should be carried out (and compliance signed for) by 11 July 2023. There is often a slight anomaly between most aircraft with a Certificate of Airworthiness (CofA) against a Permit to Fly aircraft.

The CofA aircraft will normally have the Certificate of Release to Service in the logbooks signed by the LAE / maintenance organisation on the day the Airworthiness Review Certificate is issued and the aircraft released to service. Therefore, the AD compliance date and the CRS date are on and the same.

With a Permit to Fly aircraft, the Permit to Fly revalidation process will normally require input from a third party (LAA, CAA, BMAA etc), and therefore there will nearly always be a time delay between the signing of the Permit Maintenance Release in the logbooks and the Permit to Fly Certificate of Validity being issued.

Standard modification and LAA acceptance

It recently came to light that a news item featured some time ago in Light Aviation and subsequent advertisements on the internet, promoted a piece of aircraft equipment as being accepted for installation by LAA Engineering in accordance with an already issued LAA Standard Modification.

The item in question had been produced by the new company after the original producer (cited in the Standard Modification) had ceased production. The issue was that no acceptance had been issued by LAA Engineering for the new manufacturer to produce the parts or to claim that they were made in accordance with the Standard Modification.

If there is any doubt as to a piece of equipment being accepted on LAAadministered aircraft under the Standard Modification scheme, please contact LAA Engineering to check.

Auster: Brake back plate cracked

Auster 5 owner, Robin Helliar-Symons emailed to say that his aircraft had suffered a failure of the right hand brake back plate while taxying. Ron Neal (International Auster Club’s Technical Adviser, life-long licensed engineer and maintainer) believes this may be due to a defective batch of back plates, as the problem only started in the 1970s and he is only aware of right hand plates failing.

The problem was originally brought to owner’s attention via an RF Saywell Service Bulletin (RFS/AUS/3) and mandated by CAA Airworthiness Directive CAA AD 015-11-80. The SB calls for an inspection every 100 hours or at the annual inspection, whichever occurs first.

Robin kindly submitted photographs showing the failure before and after dismantling.

Ballistic parachute recovery system installations

Right Check Section S SubSection K for the BPRS placard requirements.

In previous Engineering Matters, it has been mentioned that CAA G-INFO now records information about Ballistic Recovery Parachute Systems (BPRS) when fitted to a particular aircraft. This can be used by the emergency services to ascertain if an aircraft that has been involved in an incident, has, or may have, a BPRS system fitted.

Another point worth highlighting as a reminder to builders, owners, operators and Inspectors of BPRS-equipped aircraft, is that in 2019, the CAA issued Mandatory Permit Directive MPD 2019-005 mandating BPRS warning placards to be fitted in accordance with the requirements of BCAR Section S, Sub-Section K.

As this is a Mandatory Permit Directive, the aircraft should not be flown or the Permit to Fly be revalidated if the placarding does not comply with the Section S requirements. Placard sets are available from the LAA via the online shop.

If an aircraft has a BPRS system installed, at the time of the Permit to Fly revalidation inspection, Inspectors should also check that G-INFO records the correct information for the aircraft and that the installation has been fitted as an LAA-accepted modification.

Van’s Aircraft stick boot service bulletin

Ideally, a cockpit will be a completely sealed environment where, if something is loose, it cannot find its way to the aircraft’s control systems, possibly causing a restriction.

One of the areas of concern is around control columns where they may pass through a seat cushion, or through the cockpit floor or a bulkhead.

To this end, Van’s Aircraft have highlighted the issue and published Service Letter 00060 recommending the installation of ‘stick boot covers’ to all RV models. While this Service Letter is produced with the Van’s aircraft types in mind, the information contained within may well be useful to owners of other aircraft types.

LAA Engineering charges

LAA Project Registration

Kit Built Aircraft

Plans Built Aircraft

Initial Permit issue

Up to 450kg

451-999kg

1,000kg and above £650

Permit Revalidation (can now be paid online via LAA Shop)

Up to 450kg £170

451-999kg £220

1,000kg and above £260

Factory-built gyroplanes* (all weights) £275

*Gyros note: if the last Renewal wasn’t administered by the LAA, an extra fee of £125 applies

Modification application

Prototype modification minimum £60

Repeat modification minimum £30

Transfer

(from C of A to Permit or CAA Permit to LAA Permit)

Above Flightline Interiors produce the RV-12 interior trim kit for Van’s Aircraft and after the UK builder of this aircraft requested some stick boots from them, they now offer them as part of the trim kit.

Recent Alerts & AILs

Please note the Engineering section of the LAA website has the most current information.

LAA TSB: TSB-001-2022 and above

Four-seat aircraft

Manufacturer’s/agent’s type acceptance fee

Project registration royalty

Category change

Group A to microlight

Microlight to Group A

Change of G-Registration fee

Issue of Permit documents following G-Reg change

Replacement Documents

Lost, stolen etc (fee is per document)£20

PLEASE NOTE: When you’re submitting documents using an A4-sized envelope, a first-class stamp is insufficient postage.

Applicability: All Europa aircraft

Europa: Door latch system stop

CAA MPD: 2022-003

LAA AIL: MOD/247/012

LAA Alert: LAA/AWA/21/08

Note: CAA MPD 2022-003 has now been corrected as of 22 June 2022

MT-PROPELLER ENTWICKLUNG GmbH

Applicability: MTV-( ) Variable Pitch Propellers

Subject: Propeller Blade Lag Screw Replacement

EASA AD 2022-0134

Note: Please see the MT Propeller TADS P17 link to the ‘EASA AD Safety Publishing Tool’ for further info.

SLING

Applicability: All Sling aircraft types and serials

Subject: Eyebolt inspection and conditional replacement Sling Service Bulletin #0020

Note: It has been found that the eyebolts fitted in the control system of certain Sling aircraft may fail to meet the manufacturer’s specification in regard to fatigue life. Such eyebolts are identifiable by the narrowness of the neck of the eyebolt above the bolt thread. This service bulletin details the procedures for inspection and replacement of such eyebolts in the various control systems.