Light Aircraft MaintenanceJoseph Ryan

0729841

Abstract

This report deals with the subject of light aircraft maintenance. It explains the classification ‘light aircraft’

and explains what qualifies as a light aircraft. It investigates the regulations surrounding the maintenance of

light aircraft and what laws are in place. It then looks at the subject of the actual maintenance performed on

light aircraft and what tasks are involved. It concludes that all aspects of light aircraft maintenance in Europe

is regulated by EASA. It also concludes that the maintenance of a light aircraft is the responsibility of the

owner/operator of the aircraft.

Contents

1. Introduction………………………………………………………………………..Pg.1

2. Regulation………………………………………………………………………….Pg.1

3. Aircraft Maintenance Personnel...………………………………………………..Pg.2

4. Maintenance of Light Aircraft……………………………………………………Pg.3

- Pre-flight and Check A……………………………………………………....Pg. 4

- 50 Hour Maintenance Check………………………………………….……..Pg. 4

- 150 Hour Maintenance Check……….……………………………….…...Pg. 4

- Annual Check…………………………………………………………...….Pg. 6 5. Unscheduled Maintenance…………………………………………………..…….Pg. 6

6. Conclusions…………………………………………………………………………Pg. 6

Introduction

A Light Aircraft is defined as any aircraft having a max gross take-off weight of 12,500 lb (5,670 kg) or less.

Light Aircraft are used for many purposes. These include recreational flights, cargo and passenger transport

and touristry. An example of a light aircraft would be a Cessna 120. In fact, Cessna aircraft make up a

significant percentage of the light aircraft market. The majority of light aircraft are piston prop aircraft,

usually driven by a reciprocating engine and usually with a single propeller. Aircraft near the upper limit of

this classification may be twin prop. Since 2004 in the US, a new sub-classification of light aircraft was

defined by the FAA (Federal Aircraft Authority) which make up a large proportion of light aircraft. These

are LSA (Light Sport Aircraft). A LSA is defined by the FAA as being an aircraft with a maximum gross

takeoff weight of 1,320 lb (600kg) (1,430lb/650kg for sea-planes), a maximum airspeed of 120 knts, a

maximum two-person seating capacity, a single reciprocating engine or electric motor, non-pressurised cabin

and a maximum stall speed of 45 knts. LSA are used generally for recreational use and may sometimes

include gliders, powered parachutes and lighter than air craft such as balloons. In most other countries, a

similar classification may be referred to as ‘microlight’ or ‘ultralight’.

Fig 1. Cessna 180: Typical Light Aircraft

Regulation

Maintenance of light aircraft is regulated, similarly to commercial aircraft, by the particular airworthiness

authority in that country. In America it is controlled by the FAA, in Canada by Transport Canada and in

Europe by the European Aviation Safety Agency (EASA). This report will deal mainly with maintenance

regulations under EASA. EASA is a division of the European Union, created in 2003 to replace the existing

JAR (Joint Aviation Authorities). It helps the EU draft legislation relating to aircraft operation and safety,

regulates type-certification of aircraft and aircraft parts and regulates the enforcement of these rules.

EASA regulations relating to light aircraft maintenance can be found in EASA Regulation

EC2042/2003 Part M. Part M is a legal regulation, brought into force on 20 th November 2003 (Except

Subpart I), which provides a universal standard for light aircraft maintenance in Europe. Part M is divided

into several subparts from A through to I. Subpart A is a general description of the regulations. Subpart B

basically states that the owner/operator of the aircraft is solely responsible for the continued airworthiness of

the aircraft and no one else. Subpart C deals with the continuing airworthiness of aircraft and deals with the

regulations for light aircraft maintenance programmes. Subpart D deals with the standards expected of

maintenance providing organisations. Subpart E deals with the regulations of individual aircraft components.

Subpart F deals with the regulations regarding the requirements for an organisation to be considered an

approved maintenance organisation for light aircraft. (The regulations for large aircraft, i.e. >5,700kg can be

found in Part 145). To be a subpart F approved maintenance organisation, the company must write, submit

and keep updated a MOE (Maintenance Orgaisation Exposition). This is a documented set of maintenance

procedures by which the company operates. Subpart G deals with the regulations relating to CAMOs

(Continuing Airworthiness Management Orani2258822sations). A CAMO can not only perform maintenance

on an aircraft but can approve it’s own maintenance programmes and issue and extend Airworthiness Review

Certificates. Subparts H and I detail the regulations regarding Certificates of Release to Service (signed after

completion of maintenance) and Airworthiness Review Certificates (issued by EASA as of September 2009).

Making sure the aircraft is kept in a continual airworthy state is essentially the golden rule taken from

Part M. The owner/operator is the person solely responsible for this. They are responsible for making sure

that a certified person/organisation carries out any maintenance checks. They are also responsible for

ensuring that all maintenance checks are properly recorded and detailed in the relevant log book(s) and that

the aircraft does not fly until a certificate of release has been signed and is still valid for the time period in

question.

Aircraft Maintenance Personnel

As mentioned above, all maintenance procedures must be carried out by qualified aircraft maintenance

personnel. The certification of maintenance personnel is also controlled by EASA and the regulations

relating to light aircraft maintenance personnel are found in Regulation 2042/2003 Part 66. Part 66 is based

on the older Joint Aviation Regulation (JAR) system. Complementing Part 66 is Part 147, which details the

regulations regarding the approval of a certified training school for aircraft mechanics. There are three main

categories of training for aircraft mechanics.

Category A: Line Maintenance Mechanic. This is the most basic form of license. It allows the

mechanic to issue release certificates for an aircraft for minor maintenance tasks. The only tasks that

the mechanic is permitted to perform are tasks which they have experience performing for their

company and have been issued certification allowing them to perform such tasks.

Category B1/B2: Line Maintenance Technician. A B1 category license permits the technician to issue

release certificates for an aircraft after maintenance on aircraft structures, powerplants, and electrical

and mechanical systems. A B2 license is similar but relates to avionics and electrical systems.

Category C: Base Maintenance Engineer. This permits the Engineer to perform all base maintenance

tasks on an aircraft that they are certified for and issue certificates of release afterwards.

This system is similar to the American FAA system however, it differs in one way. In Europe, any Part 66

license holders cannot operate under their own qualifications and approve their own work. They must work

under an EASA approved maintenance organisation. For commercial aircraft maintenance, the regulations

are controlled by Part 145. For light aircraft maintenance however, an organisation does not have to be part

145 approved but only Subpart F approved, as long as it restricts it’s maintenance activities to aircraft under

5700 kgs. To qualify as a subpart F organisation, the company must keep an MOE as mentioned above. They

must also have an Accountable Manager who is responsible for ensuring that all maintenance required by a

customer can be carried out up to the standards of Part M. All personnel working for the company are

required to have relevant background, experience and qualifications. Also the company should have staff

who are qualified to issue M.A. 612 and M.A. 613 certificates of release.

Maintenance of Light Aircraft

The actual maintenance procedures performed on a light aircraft will vary slightly with the type of aircraft

and the manufacturer’s or type-certificate holder’s instructions. However the basic essential maintenance

tasks required on light aircraft by EASA Part M are contained in Subpart C. This forms the basis for Air

maintenance programs which will differ from country to country. In the UK they are given in the CAA

LAMS (Civil Aviation Authority Light Aircraft Maintenance Schedule) and LAMP (Light Aircraft

Maintenance Programme). In Ireland, they are outlined in the IAA GAMP (Irish Aviation Authority General

Aircraft Maintenance Programme). The owner/operator is responsible for seeing that the scheduled

maintenance checks contained in the programme are carried out, using the methods, techniques and standards

described. Any directives or recommendations issued by the type-certificate holder of the aircraft must also

be implemented. Where the type-certificate holders instructions differ from the programme, the certificate

holders takes priority. These are grouped into 5 different checks which must be completed after a specified

time period, with some permitted variations. Each check incorporates all tasks from the preceding checks,

plus additional tasks.

Pre-Flight Check and Check A

The pre-flight check and Check A are similar in respect to the frequency with which they must be completed.

However pre-flight checks will vary greatly with each aircraft and practically no two are the same. The exact

procedure for each pre-flight check is carried out in accordance with the individual aircraft’s Airplane Flight

Manual. This must be carried out exactly as described in the manual before every flight.

Maintenance Check A does not have to be completed before every flight but must be carried out

before the first flight of the day. Check A is a basic check of the general security and safety of the craft

before it flies. The majority of this check relies on visual observation of the aircraft. The first step is a general

visual check around the aircraft to ensure there is no obvious damage to the body, and to remove any ice

snow or frost, if present. An inspection of the interior of the aircraft should be done to ensure that all loose

equipment or miscellaneous items are properly stowed and all the aircraft’s documentation is present and

correct. The next step is a check of the powerplant/engine. It is especially important if the aircraft is not in

regular use to find out if it has been turned over weekly or run fortnightly. The engine should then be turned

by hand to check if the compression is normal. A brief inspection of the engine itself should then be

undertaken, firstly inspecting for any signs of leaking, overheating or any major wear. The oil level should

then be checked, along with the cleanliness of the air filter, and finally the security of all the engine

components, cowlings and access panels should be ensured. The fuel system should also be inspected to

ensure that the interior indicator readings agree with actual quantities and to ensure the presence of no water

or foreign matter.

After this, a more thorough inspection of the aircraft body should be completed. This includes

checking the propeller blade and spinner for any signs of damage and checking the windshield for damage

and cleanliness. The wings should be given particular attention to ensure there is no damage to the flight

control surfaces. The stall warning system should also be tested to ensure it is working. The landing gear

shock absorbers should be checked for leaks and the tyres should be checked for proper inflation. Before

taking off, a thorough cabin inspection should be completed. This includes testing of all the flight and engine

controls and testing of the brakes. All the avionics and radio equipment should be tested to make sure it is

fully operational. Also the instrumentation should be compared to the ambient conditions to see if they are

giving accurate readings. Finally, checks of the safety equipment should be completed such as the seat belts

and harnesses, emergency equipment and doors locks, etc.

Some procedures contained in GAMP are only applicable to certain aircraft, for example, marine

aircraft. In this case, unique tasks such as checking the floats, water rudder system and bilge compartments

must be performed.

Fig 2. Example of Corrosion on Aircraft Structure

50 Hour Maintenance Check

This check, as the name suggests, must be completed every 50 hours of flight time or every 6 months,

whichever is sooner. A margin of variation is permitted, either a 10% allowance in flight hours or 15 days if

measured from calendar time. However this should only be applied in exceptional circumstances and should

not be deducted from the next scheduled check.

The 50-hour check is a more intensive inspection of the airplane than the A check and will take

longer. It includes all the tasks included in the A inspection mentioned above but will be more thorough. For

example, the landing gear will be inspected as in the A check but the brake linings and brake discs will be

inspected and the brake fluid and tyres serviced. Servicing also is carried out elsewhere: for example, any

hydraulic, pneumatic or vacuum systems are inspected and serviced if need be. Also the pitot/static systems

are inspected, cleaned and cleared of any foreign objects, then correctly re-aligned. Any systems on the

aircraft which require lubrication are re-lubricated according to the manufacturers instructions. The engine is

inspected much as in the A check, however an oil change is usually required, again in accordance with the

manufacturers instructions. A more thorough inspection of the fuel system is usually completed, taking

samples from drain points and checking for the presence of water, foreign matter or discoloration. The

battery is also usually checked and the battery replaced or the electrolyte level topped up if need be.

150 Hour Maintenance Check

The 150 hour check must be completed after every 150 flight hours and does not have a calendar equivalent.

Again, all elements of previous checks are included. This check usually involves some amount of

disassembly of the aircraft for inspection access. For example, the internal structure of the fuselage, the

floors and bulkheads must all be inspected, along with the internal corrosive protection treatments. A more

thorough inspection of the engine/powerplant is also carried out, involving some disassembly.

Annual Check

This check, carried out every twelve months involves a significant amount of disassembly, for example the

internal condition of struts, control tubes and other hollow members are inspected. Checks such as pressure

testing of various fuel/oil hoses, pneumatic systems and pitot systems are usually undertaken. Most of the

electrical systems aretested and ground-operated where possible. All instruments including altimeter and air-

speed indicator are calibrated. All avionics including everything down to microphone and headsets are tested

and calibrated. The auto-pilot is given an operational check.

Unscheduled Maintenance

Not all maintenance performed on an aircraft is a result of scheduled checks. Maintenance is often performed

on aircraft as a result of an unexpected incident such as a hard landing, lightning/bird strike or damage during

turbulence. Other reasons why maintenance may be performed are ‘snags’ encountered during normal

operation of the aircraft such as the engine failing to start, low oil pressure, low voltage warning light, etc.

Fig 3. Example of Damage Which Would Require Unscheduled Maintenance

Conclusions

All aspects of Light Aircraft Maintenance are regulated by EASA specifically EASA EC2042/2003

Part M.

The golden rule of aircraft maintenance is that the owner/operator of the aircraft is responsible for

ensuring that all maintenance is carried out according to the Light Aircraft Maintenance Schedule

relating to that country.

All light aircraft maintenance must be carried out by EASA approved technicians/ engineers

operating under the approval of an EASA approved Part F organization.

Light aircraft maintenance is organized into specific checks which must be completed regularly either

according to flying hours or calendar time, whichever comes first. These checks consist of specific

tasks which must be completed.

References

- Usher, Barry (2009) Light Aircraft Maintenance, University of Limerick, unpublished.

- Carmody, Douglas S. (1997) Airplane Maintenance and Repair, New York: McGraw Hill

- Friend, C.H. (1992) Aircraft Maintenance Management, London: Longman Scientific &

Technical

- EASA (2008) ‘Part M CAT Detailed’ available:

www. easa .eu.int/ws_prod/.../Syllabus_ PartM _CAT_Detailed_04112008.pdf

- CAA (2008) ‘CAP 411 – Light Aircraft Maintenance Schedule – Aeroplanes’ available:

www. caa .co.uk/docs/33/CAP411.PDF