Prime Aviation Consultancy

Aircraft Engine Types – Simplified Overview

1. Turbo-Shaft
Used in helicopters. Compresses air, burns fuel, spins a turbine to power a shaft connected to rotors. Ideal for hovering and rescue/military missions.
Example: Apache


2. Turbo-Prop
Used in regional aircraft. Turbine spins a propeller via a gearbox; efficient for short-range flights.
Example: ATR 72


3. Turbo-Fan
Common in commercial jets. A fan pulls air—some bypasses the core, some is combusted for thrust. Balances fuel efficiency, noise, and speed.
Example: Boeing 787


4. Turbo-Jet
Early jet engine. Air is compressed, combusted, and expelled directly for thrust. High speed, low efficiency.
Example: MiG-15


5. Ram-Jet
Works at supersonic speeds. Uses aircraft motion to compress air; no moving parts.
Example: SR-71 tech


6. Scramjet
Operates at hypersonic speeds (Mach 5+). Supersonic airflow is compressed and combusted. Still experimental.
Example: NASA X-43A


7. Rocket
Carries its own fuel and oxidizer. Works in space; essential for launches.
Example: Saturn V


8. Gas Turbine
Powers auxiliary systems and generators. Used on aircraft and in ground power applications.
Example: Airport emergency systems

A320 Engine Run-Up Procedure

(General process — exact steps may vary depending on engine type: CFM56 or V2500)

1. Pre-Engine Run Checks

Area Clearance: Ensure the run-up area is clear.

Chocks & Brakes: Aircraft chocked, parking brake ON.

Fire Extinguisher: Ground fire extinguisher ready and manned.

Run-up area communication: Ground crew informed, headset connected.

Engine Oil & Hydraulic Levels: Check within limits.

Battery Voltage: Check above minimum (usually 25V).

2. Cockpit Preparation

Power ON A/C using external power or APU.

APU Start: Start the Auxiliary Power Unit to provide bleed air.

Bleed Air Configuration:

APU BLEED: ON

ENG BLEED: OFF

PACKS: OFF

3. Engine Start Procedure (Example: CFM56 Engine)

> Start Engine 1 then Engine 2, or vice versa as per SOP.

Engine Master Switch 1: ON

Monitor N2 (high-pressure spool): Should increase.

At N2 ~20%, fuel flow starts, ignition begins.

Monitor EGT: Should rise steadily.

Monitor N1/N2, EGT, FF till engine stabilizes.

Repeat for second engine.

4. Engine Stabilization

Let engines stabilize at idle (approx. 3-5 mins).

Monitor all parameters:

N1/N2 RPM

EGT (Exhaust Gas Temp)

Oil pressure/temp

Fuel flow

Vibration levels

5. High Power Run-Up (if required)

Gradually increase thrust to required power setting (e.g., 70-85% N1).

Maintain for 2-3 minutes if vibration, performance, or troubleshooting is needed.

Observe all readings.

6. Engine Shut Down

Reduce thrust levers to idle.

Let engines idle for 3 minutes for cooling.

Engine Master Switch: OFF

Monitor N2 drops to 0.

Repeat for other engine.

7. Post Engine Run

Record all engine parameters.

Inspect for leaks, unusual sounds, or damage.

Complete maintenance log entries.








(Maintenance, Repair, Overhaul)

✈️ What Does AOG Mean?

AOG is a term used in aviation maintenance and operations to indicate that an aircraft is grounded due to a technical issue and cannot fly until the problem is resolved. It's considered a high-priority status, often triggering an urgent response to minimize downtime.

🛠️ When Is AOG Declared?

AOG is declared when:

▪️A critical component has failed

▪️There is a system malfunction that affects airworthiness

▪️Required maintenance cannot be deferred

▪️The aircraft is not compliant with operational or regulatory standards

⚡ Why Is AOG Important?

▪️Delays operations and disrupts flight schedules

▪️Costly for operators due to lost revenue and potential penalties

▪️Often leads to emergency maintenance actions and priority logistics for parts and support

🔧 AOG Response May Involve:

▪️Priority parts shipment (couriers, charters, etc.)

▪️Dispatch of maintenance teams or engineers (known as "go teams")

▪️Coordination between MROs, OEMs, and logistics providers

▪️Temporary aircraft swaps or rerouting

MEL Category (A, B, C, D) along with real-world examples, usage, and rectification requirements:

The MEL allows an aircraft to be dispatched with certain inoperative equipment under specific conditions, without compromising safety.

Category A – Time Specified by MEL Item

Rectification Time:
Defined individually per MEL item — it could be 1, 3, 10 days, etc.

Examples:
Weather radar (if not required for VMC conditions)
Lavatory smoke detector (if aircraft is flying short haul)

Notes:
Rectification time and operational limitations are custom-set per equipment
Deferment may be repeated, subject to conditions

Category B – Must Be Fixed Within 3 Days

Rectification Time:
3 calendar days (excluding the day of discovery)

Examples:
One VHF communication system (when two are required)
Flight deck reading light (if required for night operations)

Notes:
Cannot be extended without specific MEL provisions
Impacts secondary systems that are still important

Category C – Must Be Fixed Within 10 Days

Rectification Time:
10 calendar days

Examples:
One of two Air Conditioning Packs
Standby compass light

Notes:
Allows dispatch with reduced redundancy or non-critical defects
Common for aircraft with built-in system duplication

Category D – Must Be Fixed Within 120 Days

Rectification Time:
120 calendar days

Examples:
Cabin reading light
Decorative panel

Notes:
Non-essential equipment
Does not affect airworthiness, safety, or legal dispatch capability

Important MEL Considerations

Flight Crew Actions:
Must follow required operating procedures (e.g., placarding, system isolation)

Maintenance Actions:
Logbook entries, deferral tracking, and return-to-service steps required

Extensions:
Some MELs may allow one-time extensions depending on regulatory approval (rare for B/C)

Effect on Dispatch:
MEL must be consulted before every flight — if any item is deferred, aircraft may require operational limitations or crew procedure changes.

A CHECK – Light Check (Line Maintenance)

Interval: Every 400–600 flight hours or ~1–2 months
Downtime: 6 to 24 hours
Where: Performed at line stations or hangars

Aircraft Interior:
Check passenger seats, oxygen masks, cabin lighting
Emergency equipment inspection (life vests, fire extinguishers)

Cockpit
System BITE (Built-In Test Equipment) checks
CVR (Cockpit Voice Recorder) & FDR (Flight Data Recorder) test

Engines & APU
Oil levels, leaks, fan blade inspection
APU operational test

Landing Gear
Tire pressure, brake wear, strut extension

Avionics (B2 role)
Navigation/communication test
Fault memory check

Fluids & Filters
Replenish hydraulic, engine oil, potable water
Replace filters if needed

B CHECK – Intermediate Check (Rare in Modern Programs)
Interval: Every 6–8 months
Downtime: 1 to 3 days

Key Tasks:
Includes all A-check tasks plus:
Systems Functional Checks:

Electrical systems
Avionics & air data computers
Auto flight & autopilot system tests

Flight Controls & Hydraulic Systems:
Movement check
Hydraulic leak checks

Lubrication & Cleaning:
Deeper cleaning of components
Lubrication of hinges, latches, actuators

Corrosion Prevention:
Initial inspection and treatment for visible corrosion

Note: Many airlines integrate B-check items across multiple A-checks.

C CHECK – Heavy Check (Base Maintenance)
Interval: Every 18–24 months or 6,000 flight hours/cycles
Downtime: 1 to 2 weeks
Where: Performed in large hangars with extensive support tools

Key Tasks:
All A + B-check tasks, plus:

Structural Inspections:
Fuselage skin, wing root, empennage, cargo areas
High-intensity corrosion and fatigue inspection

Systems Overhaul:
Air conditioning, pressurization, fire protection systems
Oxygen generation and distribution system tests

Landing Gear & Brakes:
Detailed visual and NDT (non-destructive testing)
Brake unit removal and inspection

Flight Controls & Actuators:
Detailed check of control surfaces, hinges, actuators

Avionics Systems:
Deep fault analysis, updates, and calibration
Full inspection of TCAS, GPWS, ELT, NAV systems

Interior Refurbishment:
Replacement of worn panels, carpet, and passenger systems

D CHECK – Heavy Maintenance Visit (HMV)
Interval: Every 6–10 years
Downtime: 4 to 8 weeks
Where: Specialized heavy maintenance or overhaul facilities

Key Tasks:
Complete aircraft disassembly and teardown

Structure:
Paint removal for complete fuselage inspection
Detailed NDT checks for cracks, corrosion, fatigue
Repairs, modifications, or structural replacements

Engines:
Complete engine removal, borescope, and overhaul (if needed)

Landing Gear:
Full overhaul or exchange of landing gear components

Wiring & Avionics (B2 intensive work):
Routing inspection, continuity checks, replacement
System reprogramming and software upgrades

Cabin:
Major interior refurbishment – new seats, galleys, lavs

Compliance:
Major Service Bulletins (SBs), Airworthiness Directives (ADs), modifications

General Aviation Abbreviations:

A/C – Aircraft
AOG – Aircraft on Ground (Urgent Maintenance Required)
ATC – Air Traffic Control
PIC – Pilot in Command
SIC – Second in Command
VFR – Visual Flight Rules
IFR – Instrument Flight Rules
NOTAM – Notice to Airmen (or Air Missions)
ICAO – International Civil Aviation Organization
FAA – Federal Aviation Administration

Aerodrome & Ground Operations:

ACFT – Aircraft
AD – Aerodrome
AIP – Aeronautical Information Publication
FOD – Foreign Object Debris/Damage
ILS – Instrument Landing System
PAPI – Precision Approach Path Indicator
RESA – Runway End Safety Area
RFFS – Rescue & Fire Fighting Services
SMS – Safety Management System
TSR – Temporary Speed Restriction

Regulations & Certifications:

MRO – Maintenance, Repair & Overhaul
Part 145 – Approved Maintenance Organization Regulation
Part 147 – Approved Training Organization Regulation
Part 66 – Aircraft Maintenance License Regulation
C of A – Certificate of Airworthiness
C of R – Certificate of Registration
MEL – Minimum Equipment List
MMEL – Master Minimum Equipment List
POH – Pilot’s Operating Handbook
AFM – Aircraft Flight Manual

Air Traffic & Navigation:

ATIS – Automatic Terminal Information Service
CTA – Controlled Airspace
CTR – Control Zone
SID – Standard Instrument Departure
STAR – Standard Terminal Arrival Route
METAR – Meteorological Aerodrome Report
TAF – Terminal Aerodrome Forecast
QNH – Altimeter Setting for Sea Level Pressure
QFE – Altimeter Setting for Airfield Pressure

Aircraft Performance & Systems:

MTOW – Maximum Takeoff Weight
MLW – Maximum Landing Weight
TAS – True Airspeed
IAS – Indicated Airspeed
VS – Stall Speed
V1 – Decision Speed for Takeoff
VR – Rotation Speed
V2 – Takeoff Safety Speed

Flight & Safety Terms:

TCAS – Traffic Collision Avoidance System
ELT – Emergency Locator Transmitter
GPWS – Ground Proximity Warning System
EICAS – Engine Indication & Crew Alerting System
ECAM – Electronic Centralized Aircraft Monitoring
RA – Resolution Advisory (TCAS Alert)
TAWS – Terrain Awareness Warning System

Receiving an Aircraft After a Flight: Key Considerations for Aircraft Engineers

When an aircraft arrives at the maintenance bay after a long flight, it is the engineer’s responsibility to ensure it is properly received, inspected, and prepared for the next operation. This process requires attention to detail, adherence to procedures, and effective communication with the flight crew.

1. Expectations Upon Arrival

As the aircraft taxis into the bay, engineers should anticipate the following:
• Tire and Brake Wear: Long flights generate heat and stress on landing gear components.
• Fluid Leaks: Hydraulic, fuel, or oil leaks may be present due to extended operation.
• Bird Strikes or Structural Damage: The aircraft may have encountered birds or foreign objects.
• Crew Reports: Pilots may report technical issues requiring immediate attention.
• Cabin Issues: The cabin crew may highlight pressurization, lighting, or system malfunctions.

2. Steps to Follow Upon Aircraft Arrival

a. Establish Safety Precautions
• Ensure chocks are in place before shutting down engines.
• Confirm ground power or APU operation if needed.
• Set up safety cones around the aircraft to prevent unauthorized access.

b. Conduct Visual Inspections
• Perform a walk-around check for any visible damage, leaks, or missing panels.
• Inspect landing gear and tires for wear, cuts, or deflation.
• Check pitot-static probes and sensors for contamination or blockage.

c. Review Aircraft Logbook & Pilot Reports
• Verify any recorded discrepancies or maintenance actions required.
• Discuss findings with the flight crew to clarify any reported issues.

d. Perform System Checks
• Ensure hydraulic pressure levels are within limits.
• Check fuel quantity and any signs of leaks in the wing areas.
• Inspect engine nacelles for oil leaks or abnormal wear.

3. Key Focus Areas During Inspection
• Engines & Exhaust: Look for oil leaks, damage, and unusual soot buildup.
• Flight Control Surfaces: Ensure no obstructions, dents, or signs of damage.
• External Lights: Confirm all navigation, landing, and taxi lights are functional.
• Cargo & Passenger Doors: Ensure proper latching and sealing.

4. Coordination & Documentation
• Communicate findings with the technical team and maintenance control.
• Log all discrepancies and actions taken in the maintenance system.
• If necessary, initiate a more detailed inspection or troubleshooting process.

Conclusion

Receiving an aircraft after a long flight is a critical task that ensures continued safety and reliability. By following structured procedures, engineers can effectively identify potential issues, prevent delays, and maintain airworthiness

✈️ PROPELLER BLADE ELEMENTS✈️

📌The typical propeller blade can be described as a twisted airfoil of irregular planform.

📌Two views of a propeller blade are shown in the image above.

📌For purposes of analysis, a blade can be divided into segments located by station numbers in inches from the center of the blade hub.

📌The cross-sections of each 6-inch blade segment are shown as airfoils on the right side of the image.

🔖Also identified above are the blade shank and the blade butt.

📌The blade shank is the thick, rounded portion of the propeller blade near the hub and is designed to give strength to the blade.

📌The blade butt, also called the blade base or root, is the end of the blade that fits in the propeller hub.

🔖The blade tip is the part of the propeller blade farthest from the hub, generally defined as the last 6 inches of the blade.








゚ Highlight

The Art of Perfect Landing

Mastering traffic pattern procedures is essential for safe and efficient operations at non-towered airports, providing a standardized flow of aircraft within the terminal area and enhancing predictability in a potentially hazardous environment. Let’s delve into the intricacies of traffic patterns, transforming the once perilous rectangular course into a streamlined pathway to successful landings.

Departure/Upwind Leg (500-700ft AGL)
Depart the runway and ascend to 500-700 feet above ground level (AGL). This phase offers a panoramic view of the airstrip and surroundings, enabling you to assess conditions and chart a successful approach.

Crosswind Leg (700-900ft AGL)
Transition smoothly from the upwind leg, maintaining 700-900 feet AGL. Here, refine your heading and position, preparing for the critical downwind leg.
On VFR, extend the landing gear before downwind entry. Perform GUMPS. This slows the aircraft and allows trimming for the gear down condition, as well as allowing a slower speed for purposes of blending with other traffic.

Downwind Leg (Established at TPA - 1000ft AGL)
Descend to pattern altitude, usually 1000 feet above airport elevation, and establish on the downwind leg. This segment parallels the runway, providing stability in the dynamic environment.

Base Leg
Initiate a controlled descent from pattern altitude to 500-600 feet AGL. Adjust throttle and configuration, preparing for the transition to final approach.

Final Approach
Align precisely with the extended runway centerline, maintaining a speed approximately 1.3 times the stall speed (Vso) of your aircraft. Observe glideslope / PAPIs (if available), On an IFR flight, perform GUMPS before or at final approach fix (assuming an instrument approach is being performed, extend the gear at glideslope intercept for a precision approach or at the final approach fix on a non-precision approach). Doing so will help you set up a stabilized approach. Descend smoothly towards the runway, maintaining 500-600 feet AGL for a graceful landing.

In aviation, flexibility is paramount as each landing presents unique challenges and characteristics. Adaptation to changing variables is crucial, aiming to gracefully bleed off excessive airspeed and altitude. Remember, always be mindful of wind direction.

* Note: There is a voluntary safety program / recommendation from the FAA that encourages, but does not require, pilots to turn landing lights on at or below 10,000’ especially when within 10 nm of an airport. This recommendation of 10K is actually being adopted as a minimum. A friend who flies for FedEx told me that they turn them on at or below 25K. In the old days when bulbs had a finite and short life, and were somewhat expensive, GA pilots who fly below 10,000 ft used to turn them off due to cost. With the LEDs now lasting a lot longer (“forever”), keeping them on all the time is indeed a good practice (similar to cars’ daylight running lights which come on as the vehicles get started).

Forgot to say that there are 3 rules to obtain the best possible landings. Unfortunately no one knows what they are …



Taxiway & Runway location.
(Identifies where the taxiways and runways are)

Runway safety area OF & Runway approach area
Boundary.
(Identifies exit boundary for a runway safety area / OFZ / or runway approach)

ILS Critical area/ POFZ Boundary.
(Identifies ILS critical area exit boundary)

Direction taxiway.
(Denotes the direction or designation of intersecting runway)

Runway exit.
(Denotes the direction of each exit taxiway from the runway)

Outbound/Inbound destination
(Outbound- Define directions to departing aircrafts)
(Inbound-Define directions to approaching aircraft)

OFZ=Obstacle-free zone

Cc: Euro Aviation TV