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EASA Part-66 Module 13 Cats B2 · B2L

Aircraft Aerodynamics, Structures & Systems EASA Part-66 — Module 13 Practice Questions

Module 13 is the B2 avionics omnibus — theory of flight, airframe structures, electrical power, autoflight, comms, navigation, instruments and integrated modular avionics in one 188-question paper. Below: what the syllabus covers, exam format, and seven sample questions in the same style you'll meet on exam day.

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Every question comes with a worked, EASA-grounded explanation — understand why, don't just memorise.
955
Questions in bank
5
Syllabus sections
235 min
Exam time (B1/B2)
75 %
EASA pass mark

Syllabus at a glance

Full Module 13 syllabus
Section 13.5
Electrical Power
  • Batteries: lead-acid, NiCd, Li-ion — servicing & SG checks
  • DC & AC generation: alternators, IDGs, TRUs, inverters
  • Distribution, bus systems & circuit protection
  • Emergency power: RAT, battery bus, load shedding
Section 13.8
Instruments
  • Pitot-static: ASI, altimeter, VSI & alternate static
  • Gyroscopic instruments & flux-valve compass systems
  • EFIS / EICAS / ECAM, ADC & ADIRU architecture
  • Stall warning, AoA indicators, FDR & CVR
Section 13.4
Communication / Navigation
  • VHF, HF & SATCOM; ELT and audio integrating systems
  • VOR, ILS, ADF/NDB, DME & radio altimeter principles
  • GPS/GNSS, RNAV, FMS & inertial reference (IRS)
  • Surveillance: transponder modes, ADS-B, TCAS, TAWS
Section 13.3
Autoflight
  • Autopilot architecture: sensing, computing, output
  • Flight director, yaw damper & automatic trim
  • Autothrottle, ILS coupling & autoland (CAT I/II/III)
  • Helicopter SAS & automatic stabilisation equipment
Section 13.20
Integrated Modular Avionics
  • IMA concept, ARINC 653 partitioning & common resources
  • Line Replaceable Modules (LRMs) & software loading
  • Data buses: ARINC 429, ARINC 664/AFDX
  • Advantages over federated avionics architectures

Three classic exam-day traps

Lead-acid SG without temperature correction

Specific gravity readings on a lead-acid cell are only meaningful when corrected to a reference temperature — a warm battery reads artificially low and gets “condemned” in error.

TCAS interrogation vs reply frequencies

TCAS interrogates other transponders on 1030 MHz and listens for replies on 1090 MHz — the same SSR pair, but candidates routinely swap them under exam pressure.

IAS, CAS and TAS in the climb

Holding a constant indicated airspeed in the climb does not mean true airspeed is constant. As density falls with altitude, TAS rises even though the ASI needle stays put.

What Module 13 covers — in plain English

Module 13 is the largest single paper in the EASA Part-66 syllabus. It bundles aerodynamics, airframe structures and almost every aircraft system — electrical, autoflight, comms, navigation, instruments, integrated modular avionics, lights, on-board maintenance systems, air conditioning, fire protection, fuel, hydraulics, ice/rain protection, landing gear, oxygen, pneumatics and more — into one 188-question, 235-minute examination at knowledge level 2–3. It is the B2 avionics analogue of the B1 mechanic’s Modules 11/15/16/17.

Module 13 is sat by category B2 and B2L candidates only. Category A, B1 and B3 engineers do not sit this paper. B2L candidates take a subset broken down by system rating (Basic, COM/NAV, Instruments, Autoflight, Surveillance, Airframe Systems) — the same question pool, just partitioned by the rating being licensed. EASA permits the 188 questions to be split into two sittings where this is administratively convenient.

The depth of coverage is what catches most candidates out. Autoflight, comms, navigation, instruments and electrical power are all examined at knowledge level 3 — you must be able to apply theory, interpret schematics, troubleshoot failures and explain interactions between systems, not merely recognise terminology. Structures, fire protection, pneumatics, ice/rain and a few smaller systems sit at level 2. Detailed per-section knowledge levels and ATA chapter mappings are on our Module 13 syllabus page.

These samples are drawn from our live Module 13 question bank of 955 questions. The full timed practice quiz draws 188 questions per attempt (or 0 for Cat A), scored against the official EASA 75 % pass mark, with weak-area tracking across attempts.

7 free sample questions

Click "Reveal answer + explanation" after you've picked.

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Q1 Electrical Power · Batteries

What must be taken into account when measuring the SG or relative density of a lead acid battery?

  1. A The temperature
  2. B The ambient pressure
  3. C The ambient humidity
Reveal answer + explanation Hide answer
Correct answer: A — The temperature
Electrolyte density varies with temperature, so a hydrometer reading must be corrected to a reference temperature (typically 15°C or 25°C). A warm battery reads artificially low and can be wrongly declared discharged if the correction factor is ignored.
Q2 Instruments · Pitot-Static

The applied pressure to an ASI varies with the

  1. A square of the speed
  2. B square root of the speed
  3. C cube root of the speed
Reveal answer + explanation Hide answer
Correct answer: A — square of the speed
Dynamic pressure q = ½ρV², so the differential pressure sensed by an ASI rises with the square of true airspeed. That is why the ASI dial is non-linear — the markings bunch up at low speed and spread out at high speed.
Q3 Instruments · Airspeed

An aircraft in climb maintains the same IAS. What is it`s true airspeed?

  1. A Higher than its IAS
  2. B Lower than its IAS
  3. C The same as its IAS
Reveal answer + explanation Hide answer
Correct answer: A — Higher than its IAS
IAS is derived from dynamic pressure, which depends on air density. As altitude increases density drops, so to produce the same q = ½ρV² the true airspeed must rise. Rule of thumb: TAS ≈ IAS + 2% per 1,000 ft.
Q4 Comms · VHF

The international emergency frequency used in VHF Comms is

  1. A 131.55
  2. B 121.5
  3. C 118.00
Reveal answer + explanation Hide answer
Correct answer: B — 121.5
ICAO designates 121.5 MHz as the international aeronautical emergency frequency (“Guard”), monitored by ATC units, aircraft and search-and-rescue. 243.0 MHz is the military equivalent, and 406 MHz is the modern ELT distress beacon band.
Q5 Surveillance · TCAS

TCAS transmits and receives on a frequency of

  1. A 1030 MHz and 1090mhz respectively
  2. B 1090mhz and 1030mhz respectively
  3. C 1090 MHz
Reveal answer + explanation Hide answer
Correct answer: A — 1030 MHz and 1090mhz respectively
TCAS interrogates other aircraft transponders on 1030 MHz and listens for their replies on 1090 MHz — the same uplink/downlink pair used by ground-based SSR. Mode S addressing lets it target individual aircraft rather than flooding the band.
Q6 Autoflight · Yaw Damper

The purpose of a yaw damper is to

  1. A assist the aerodynamic response
  2. B produce a co-ordinated turn
  3. C block the Dutch roll frequency
Reveal answer + explanation Hide answer
Correct answer: C — block the Dutch roll frequency
A yaw damper senses yaw rate and commands opposing rudder to suppress the lightly-damped Dutch roll mode typical of swept-wing jets. It is a stability augmentation function, not a turn-coordination aid — coordinated turns come from aileron-to-rudder crossfeed.
Q7 IMA · Data Buses

ARINC 429 operates at which speed?

  1. A 13 kb/s or 100 kb/s
  2. B 2 Mb/s
  3. C 1.3 Mb/s
Reveal answer + explanation Hide answer
Correct answer: A — 13 kb/s or 100 kb/s
ARINC 429 is a one-way, single-source/multi-sink digital bus operating at either 12.5 kbit/s (low speed) or 100 kbit/s (high speed). Higher-bandwidth designs migrated to ARINC 629 (2 Mbit/s) and then ARINC 664/AFDX (100 Mbit/s).
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Module 13 — frequently asked questions

How many questions are in the EASA Part-66 Module 13 exam?
Module 13 is not part of the Category A syllabus, so there is no Category A paper. For Category B2 and B2L candidates the exam contains 188 multiple-choice questions — the largest single paper in the whole EASA Part-66 syllabus, covering aerodynamics, structures and almost every aircraft system.
What is the pass mark for EASA Part-66 Module 13?
The pass mark is 75%, the same as every EASA Part-66 module. With 188 questions you can afford to get up to 47 wrong and still pass. There is no negative marking, so always attempt every question rather than leaving any blank.
How long is the Module 13 exam?
Category B2 and B2L candidates are allowed 235 minutes for the 188-question paper, which works out to 1 minute 15 seconds per question. Module 13 is not sat by Category A, so no Category A time limit applies. At 188 questions it is by far the largest single Part-66 module exam, so pacing and stamina matter as much as raw knowledge.
Which EASA licence categories require Module 13?
Module 13 is sat by Category B2 and B2L avionics candidates only. Category A, B1 and B3 engineers do not take this paper — it is the B2 avionics analogue of the B1 mechanic’s airframe and powerplant modules. B2L candidates take a subset of the same question pool partitioned by the system rating being licensed.
What does Module 13 cover, and what do students find hardest?
Module 13 bundles theory of flight, airframe structures, electrical power, autoflight, communications, navigation, instruments and integrated modular avionics into one paper. The depth catches most candidates out: autoflight, comms/nav, instruments and electrical power are examined at knowledge level 3, so you must apply theory and troubleshoot, not just recognise terms. Common traps include forgetting to temperature-correct a lead-acid battery specific-gravity reading, swapping the TCAS interrogate (1030 MHz) and reply (1090 MHz) frequencies, and assuming a constant indicated airspeed in the climb means a constant true airspeed — TAS actually rises as density falls.
How should I revise for Module 13?
Because Module 13 spans so many systems, work through it system by system rather than trying to cover everything at once — drill electrical power, then instruments, then comms/nav, autoflight and integrated modular avionics in turn. Pay particular attention to the details examiners exploit: dynamic pressure varying with the square of speed, the 121.5 MHz emergency frequency, and ARINC 429 speeds. Use timed practice sets to build the pace needed to answer 188 questions in 235 minutes.

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15. Gas turbine engine
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Module 13 study resources

Module 13 detailed syllabus
Per Commission Regulation (EU) 2023/989
Module 13 study notes
Topic-by-topic explanations
Q&A forum
Ask about tricky Module 13 questions
EASA licence categories
A · B1 · B2 · B2L · B3 overview

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