Jet Parts 360 Blog

process of jet engine maintenance and overhaul

Before an aircraft takes flight, there is a lot of inspection and maintenance that happens both before the day of flight and a few hours prior to takeoff. Those hours before flight are very important as that is the last opportunity to catch any anomalies that need to be inspected. During these check ups, the flight crew checks on things like engine condition and lubricant levels to spot anything different from what is standard. Then there are some items that must be inspected on a cyclic schedule. These items are checked during what is known as the hot section inspection or HSI.

Hot Section Inspection

The HSI is exactly what is sounds like: it refers to the inspection of the parts in the engine that are exposed to heat and pressure of fuel combustion. The purpose of this inspection is to ensure that these components are fully functional and capable of producing rated power. These parts typically consist of compressor turbines, temperature sensors and connectors, stationary vane rings, blades of power, and the compressor inlet. If any of these items do not meet standard, then the parts will have to be disassembled and replaced.

Overhaul

The first step for the overhaul of an engine is usually the disassembling of parts. Maintenance for a jet engine will sometimes be done “on wing” but often it is necessary to remove it entirely from the aircraft. After the engine is disassembled, each part is cleaned prior to inspection and then analyzed for wear and tear. Items exceedingly worn can ultimately lead to failure of a component and will need to be replaced. Some of the testing that is performed include the dye penetration test, x-ray inspections, and electronic assessments. The entire overhaul process can take up to a few days before all the replacement parts are brought in and undergo installation and a test run. After this, if the new assembly passes inspection, the engine goes through another run for TBO (Time Before Overhaul) to certify that it is performing at standard shape.

At Jet Parts 360, owned and operated by ASAP Semiconductor, we can help you find all the unique parts for the aerospace, civil aviation, and defense industries. We’re always available and ready to help you find all the parts and equipment you need, 24/7-365. For a quick and competitive quote, email us at sales@jetparts360.com or call us at 1-708-387-78006.

how does a jet engine work in the rain?

Jet engines operate by igniting a mixture of air and fuel and using the resulting gases to produce thrust. It doesn’t take an expert to figure out that moisture can have an adverse effect on an engine’s combustion process. So what exactly happens to jet engines in inclement weather? While jet engines are not totally immune to the elements, there are many features protecting jet engines from experiencing difficulties. Flameouts are the biggest threats caused by moisture such as rain and ice. In its most basic definition, a flameout is the loss of engine power due to factors unrelated to mechanical failure. A flameout can be caused by the loss of fuel, air, or heat. While flameouts must be taken seriously, they are exceedingly rare and can be fixed mid-flight.

In addition to flameouts being extremely rare, it is highly unusual that moisture is the cause. Although rain is capable of hindering the function of a jet engine, it is rarely a noticeable effect. The majority of storms do not create enough rain or snow to disturb the engines, and the ice crystals that clouds are made of are far too small to affect function. The extreme heat of the combustion chamber provides its own defense mechanism, evaporating these minute levels of moisture almost immediately. Only very significant storms could strain a jet engine, and in those cases it is very likely that an aircraft will take a detour and circumvent the storm altogether.

Significant moisture like large hail, ice, and freezing rain are the toughest to deal with. Large hail is capable of damaging the engine or aircraft’s skin, but as it is only prevalent in large storms, it is easily avoided with a flight detour. Freezing rain is problematic since it can cause ice buildup on the engine inlet, the duct responsible for smooth airflow from all directions into the engine. If ice is able to build up, large chunks can separate and enter the engine, thereby hindering the combustion process and leading to flameout.

Each aircraft is built with a myriad of safety features that deal specifically with inclement weather and the prevention of flameouts. Engines are equipped with intricate heating systems that control the temperature of areas where ice is more likely to appear. In addition to this, the center of the engine is spotted with bits of rubber that vibrate to shake off ice that has accumulated. Igniters are a safety feature in the combustion chamber that re-ignite the mixture of fuel and air to restart the engine. They operate very similarly to spark plugs in an automobile. Standard igniters are usually turned on manually, but certain new aircraft have sensors which will start them automatically as the combustion process begins to struggle. Igniters have been utilized in a few cases to restart engines that have flamed out allowing aircraft to continue safely to their desired locations.

The safety of jet engines and flight in general cannot be overstated. To learn more about jet engines and their parts, come visit our Jet Parts 360 website at https://www.jetparts360.com. There you will find our vast inventory of NSN parts, FSC parts, and CAGE Codes.
We also welcome you to contact us by phone at (708)387-7800 or email at sales@jetparts360.com.

aircraft ground support and towing

When your plane arrives at its destination and slowly moves towards the terminal, you may have noticed several different pieces of equipment waiting to service the plane. Tow tractors, cranes, dollies, and ground support personnel busying about, waiting to perform crucial maintenance on the plane you just exited. This ground support is the lifeline for successful flights.

Aircraft ground support equipment refers to the various tools and devices used to service aircrafts that aren’t in flight. This process requires a fleet of operators to adhere to precise handling rules so that the machinery they use works as intended. There are different variations of non-powered equipment such as chocks, dollies, tripod jacks, and rollers. There are also different types of powered equipment as well, such as refuelers, tugs and tractors, ground power units, container loaders, and buses.

The equipment required to service aircraft systems include power generators, cabin pressure test units, fluid servicing units, munitions loading system, and electrical testers. All of which are designed to be self-propelled, trailer mounted, or towed for ease of access and maneuverability. Ground support equipment can define the success of an entire aviation establishment, whether it be an airport or military air base. The complete servicing process must coincide firmly within industry standards while operating at a minimum life-cycle cost.

Not everything you find at a commercial airport will be found at a military airfield, which is simply due to military aircraft being equipped with items which have no translatable purpose or use in the civilian market. The most common type of ground service equipment found in a military airfield is a hydraulic loader, used to load pieces of ordnance (bullets, bombs, missiles). Dedicated military service equipment must be utterly reliable and dependable, simple to use, and quick to learn. Ground service equipment plays an integral role in the maintenance, specialized technical support, operational safety, and towing of aircraft.

types of gas turbine engines

In a typical reciprocating combustion engine, as seen in automobiles and propeller-driven aircraft, the functions of intake, compression, combustion, and exhaust all take place in the same combustion chamber. Therefore, each must have exclusive occupancy of the chamber during its part in the combustion cycle. Gas turbines, however, have separate sections for each function, and all functions are performed simultaneously without interruption.

These sections typically consist of:

An air inlet, where the air enters the engine
A compressor section
A combustion section
A turbine section
An exhaust section
An accessory section
Systems used in starting, lubrication, fuel supply, and auxiliary purposes, such as anti-icing, cooling, and pressurization

There are four gas turbine engines used to power jet aircraft: turbofans, turboprops, turboshaft, and turbojet. While turbojets were the first type of turbine engine to be developed, they are noisy and have high fuel consumption at the speeds most airliners fly at, so turbojets are fairly limited in use

Most turbine-driven aircraft use turbofan engines. A turbofan has a large fan or set of fans at the front of the engine that produces about eighty percent of the thrust from the engine, with less noise and fuel consumption. Turbofan engines have more than one shaft in the engine, with most having two. These two-shafted engines use two spools (the compressor, shaft, and turbines), divided between a high-pressure spool and low-pressure spool.

Turbofans are either low bypass or high bypass. The amount of air bypassed around the core determines the bypass ratio: if, for example, a turbofan has 100 pounds per second of air flowing through the fan, and 20 pounds per second flowing through the core, the engine has a 5:1 bypass ratio. Some low-bypass turbofan engines are used in speeds above .8 Mach, and use afterburners to increase thrust. By adding more fuel nozzles and a flame holder in the exhaust system, extra fuel can be sprayed and burned which gives large increases to thrust for a short time.

Turboprop engines are gas turbine engines that turn propellers through a speed reduction gear box. This type of engine is most efficient at 300 to 400 mph, and can use shorter runways than other aircraft. Eighty to eighty five percent of the energy that the engine produces is used to drive the propeller, while the rest exist the exhaust as thrust.

Lastly, turboshaft engines transfer horsepower to a shaft that turns a helicopter transmission or serves as an auxiliary power unit (APU). APUS are used to provide electrical power and bleed air on the ground, and as a backup generator in flight. Turboshaft engines can come in a variety of configurations and horsepower range.

jump-start: how does a jet engine’s turbine start turning?

Much like starting a car’s engine, starting the turbine engines on a commercial airliner is a complicated endeavor. When a turbine engine’s main fan in the front begins to spin, it is actually one of the latter steps in a process that ends with the engines at full power and the aircraft taking off into the sky.

The engine start-up sequence begins with the auxiliary power unit, or APU. The APU is a miniature jet engine with its own compressor, combustor, and turbine that provides electricity to the aircraft and compressed air for the air conditioning system while the aircraft is on the ground. Despite being a jet engine in design, the APU does not provide thrust to the aircraft. In addition to its other duties, the APU provides the first step in starting the jet’s main engines and causing its blades to rotate.

After passengers are onboard and buckled in, the APU begins to send compressed air to the jet’s main turbine engines. The compressed air passes through a small turbine on the outside of the engine, which causes it to spin. Attached to this turbine is a shaft which connects via gears to the main engine shaft, which begins to spin as well.

Once the main engine shaft and its blades are spinning, the pilot adds fuel to the combustor section of the engine. An electric spark then ignites the mixture of fuel and air, and the exhaust passes from the combustor out through another turbine of blades, speeding the engine up to the point that it is self-sustaining. More fuel can then be added, which speeds the engine up even more, increasing its power output and eventually enabling flight.

do you know the lifespan of an aircraft?

As you gaze into the sky and look about the horizon, an ascending airplane catches your eye— you marvel in its magnificence and can’t help but to feel inspired by the wonders of flight. The aircraft travels so effortlessly from afar, almost as if it can fly forever. As flawless as it might seem, there comes a time when every plane must be decommissioned. So, what determines the lifespan of a plane? Where do they go after they can’t fly anymore?

The determined aircraft lifespan is established by the manufacturer. It is not measured in total years of service; instead, it is calculated by the amount of pressurization cycles it endures. This refers to the amount of time that the aircraft is kept under pressure from flight, and the amount of stress put on the fuselage and wings. Short-haul flights often grant shorter lifespans while long-haul flights allow for longer lifespans. Shorter flights lead to more pressurization cycles, shortening longevity. A Boeing 747 can withstand approximately 35,000 pressurization cycles—roughly 165,000 flight hours. Airlines must decide on when to retire an aircraft based on profitability and public safety.

Airlines are continuously upgrading their aircraft due to changing tastes of consumers. There are planes that are capable of flying for several decades, however, commercial airline passengers wouldn’t be willing to pay top dollar for them without integrated advancements. Manufacturers commonly offer upgraded features which leads to a decrease in demand of older model aircraft, which also contributes to its lifespan. Airlines with the newest planes tend to have more customers flying at a given time because of increased customer satisfaction.

Decommissioned aircraft eventually make their way to the southwestern American desert that includes parts of California, Arizona, New Mexico, and Texas. Massive aircraft storage sites house these planes in arid climates which slow down the rusting process, allowing the spare parts to be used or sold later. Secondhand aircraft parts are hot commodities as most of them still function and are significantly cheaper than new ones. Almost every part of an airplane can be recycled for use in newer planes.

Engines are in high demand because their turbines contain rotating blades that must be swapped out regularly to stay in compliance with safety regulations. Trading out these blades for used ones can cost upwards of two million dollars, roughly half the price of buying new parts. Once an aircraft has been stripped of all of its usable parts, the metal frame is melted down and used as scrap. In some cases, the raw materials are repurposed. Multiple recycling operations in the US and Europe specialize in this processing. The next time you drink from an aluminum can, consider that what you’re holding may have flown across the skies at one point!

what is the main difference between connectors and conduits?

There are five basic types of Army/Navy (AN) connectors used on aircraft: Class A, Class B, Class C, Class D, and Class K. Class A-D connectors are made of aluminum while Class K is made of steel. Class A is a solid, one-piece back shell connector and is general-purpose. Class B back shell separates into two parts along the length and is used where it’s important that the soldered connectors are readily accessible. Class C is a pressurized connector and has inserts that are not removable. They are used on walls or bulkheads of equipment that is pressurized. Class D are moisture and vibration resistant and have a sealing grommet in the back shell. Class K is a fireproof connector and is usually longer than other connectors.

When frequent disconnection is required, connectors facilitate maintenance. Connectors are susceptible to corrosion because of condensation within the shell. Because of this, waterproof features have been developed. If a connector is not waterproof, it may be treated with a waterproof jelly.

There are about four steps to assembling a connector to a receptacle. The first step is to locate the proper position of the plug to the receptacle. The second is to create a slight forward pressure to start the plug into the receptacle. The third step is to push the plug in and tighten the coupling ring. And the fourth step is to use connector pliers and tighten the coupling rings. It’s important to not use force to mate connectors and receptacles; don’t use a hammer to force a plug into the receptacle and don’t use a torque wrench or pliers to lock coupling rings. Doing so can cause irreparable damage to the connectors.

And there are about three steps to disassembling a connector. The first step is to use connector pliers to loosen the coupling rings. The second step is to pull on the plug body and unscrew the coupling ring. And the third step is to protect the plugs and receptacles with caps or plastic bags; this will prevent debris from entering the items.

A conduit is a tube that protects electric wiring and is used in aircraft to protect wires and cables. It comes in metallic, nonmetallic, rigid, and flexible forms. Many installers will account for ease of use for maintenance and leave some room for possible circuit expansion in the future. Fittings are used at the end of a conduit to make it less vulnerable and if a fitting is not used, the conduit end should be flared. This will prevent wire insulation damage. It’s important to pay close attention when installing a conduit because it shouldn’t be located where it may be used as a handhold or footstep. Installers need to provide drain holes at the lowest point in a conduit run. And, the conduit needs support to prevent chafing and avoid stressing its end fittings. When a conduit is damaged, it should be replaced as soon as possible so the wires do not get damaged.

how is jet engine designed?

There are three kinds of engines that power most aircraft: piston engines, jet engines, and rocket engines. Each of these have the same basic principles; the engine mixes fuel with an oxidizer in a combustion chamber, the mixture is ignited, the burning mixture creates hot, expanding gases, and these gases will either produce thrust directly or are used to push a piston or drive a turbine. There are different variations of a jet engine, also known as a gas turbine. Most have the same five key parts: an inlet, a compressor, a combustion chamber, and a turbine with a driveshaft running through them.

Turbojets are the basic jet engine. They produce a steady amount of power and are useful for low-speed jet planes that do not have high payloads. Air passes through an inlet, is compressed to 3 to 12 times its existing pressure, fuel is added and ignited in a combustion chamber, and the hot air then passes through a turbine and is expelled past a nozzle. The turbine extracts energy and powers the compressor. An afterburner may be used to increase the temperature of the gas ahead of the nozzle, which results in the capacity for higher speeds.

Turboprop engines have the same components but transfer energy from the gas to the turbine which will then turn a shaft that drives a propeller. Thrust is produced from the rotating propeller instead of expelled gas. It has better propulsion efficiencies at speeds below 500 mph. Turboshafts are similar to turboprops, but instead of driving a propeller, it provides power to a helicopter rotor.

Most modern airliners use turbofans because they are quieter and have better fuel efficiency. They operate the same way as the previous two engines however, they have a large fan at the front of the engine. A portion of the air will pass through the gas generator and the remainder passes through the fan and is ejected directly into the jet stream or mixed with the gas-generator exhaust. This is called a bypass system and increases thrust without increasing fuel consumption.

Ramjets are in the shape of a rapidly tapering nozzle. This shape naturally compresses the incoming air, so ramjets do not have compressors or turbines. They require an assisted takeoff and are used for guided-missile systems and space vehicles. The difference between a ramjet and a scramjet is that a ramjet compresses the air and reduces it to subsonic speeds while a ramjet allows the airflow to remain supersonic and the plane can go much faster.

aircraft tow bar maintenance

Although tow bars are essential equipment for aircraft emergencies, tow bar maintenance is often overlooked. Just like with any other piece of equipment, tow bars should have a brief daily inspection and routinely scheduled thorough maintenance in order to ensure full functionality. Because there are many types of tow bars, it’s best to at least become familiar with some of the more common tow bar parts to ensure inspection goes smoothly.

Shear pins should be one of the first parts to be inspected because they carry the majority of the load when the aircraft is being pushed or towed. They are designed to have a breaking point, reducing the possibility of damage to the aircraft in the event of too much strain. The pins should be removed and checked for any sign of stress, indents, cracks, or other irregularities. The pin should be immediately replaced if any signs of strain are observed.

The head mechanism includes many moving parts which should be inspected on a regular basis. Each moving part should be carefully inspected and checked for lubrication. Improper lubrication can lead to premature wear and tear.

The tow bar body should be inspected regularly for any cracks. If any damage is observed, it should be taken to a certified welder for repairs following proper protocols and procedures. If there is any other severe damage to the body, the unit should be taken out to be serviced or replaced right away. Continued use will only result in further complications.

The wheels are typically not something that you might consider as needing inspections. The wheels have specific parts which could inhibit movement, so it’s important to make sure the lug nuts are tightened and checked for any cracks on the wheel. If any irregularities are noticed, it should be brought to attention and remedied.

components of a jet engine

Jet engines are complex pieces of machinery that propel giant metal contraptions tens of thousands of feet in the air. They’re a type of combustion reaction engine that discharge fast-moving streams of fluid and generate thrust by propulsion. They’re made of different parts: a fan, compressor, combustor, turbine, nozzle, and exhaust.

The fan, or the air inlet, is a large spinning fan made of titanium that sucks in a large quantity of air. After sucking, it speeds up the air and splits it into two parts: one that goes through the core part or through the center of the jet engine where it is acted upon by other engine components, and one that “bypasses” the core and goes through a duct that surrounds the core and produces much of the force that propels the airplane forward.

The compressor is the first component of the core. It’s made up of fans with many blades attached to the shaft and has many different stages, each consisting of rotating vanes and stationary stators. As air goes through the compressor, the heat and pressure increases, the energy is derived from the turbine and passed along the shaft, and then the compressed air is forced into the combustion chamber.

In the combustor, there are as many as 20 nozzles to spray fuel into the airstream, and the mixture of air and fuel catches fire. The fuel and oxygen burning produces hot expanding gases, leading to high temperatures and high-energy airflow.

The high-energy airflow leaves the combustor to spin the turbine, a series of bladed discs that act like a windmill. The turbines are linked by a shaft to turn the blades in the compressor and to spin the intake fan at the front. This process takes some energy from the high-energy flow. In some turbine engines, additional energy is used to drive things like the propellers, bypass fans, and rotors.

The last part is the nozzle and exhaust, where the thrust is actually produced. The hot energy-depleted airflow that passed through the turbines and the colder air that bypassed the core converge and exit the nozzle, exerting a force that propels the aircraft forward.

At Jet Parts 360, owned and operated by ASAP Semiconductor, we’re a leading supplier of all things aircraft and aviation. From engine components to cockpit instruments, we have it all. Visit our website, www.jetparts360.com, to get started on a quote.