Hats off to the jet-engine ‘medics’ who keep our planes in the sky

Aircraft engine maintenance is crucial and the engineers who carry out inspections form a high-tech army dedicated to keeping airlines operating.

Japan Airlines maintenance personnel check a jet engine at Narita International Airport in Narita, east of Tokyo. The aviation imaging equipment specialist Olympus is to set up an aircraft maintenanceShow more

While flying in a commercial jetliner is safer statistically than any other form of transport, according to research by Ian Savage, an economics professor at Northwestern University in Illinois, probably the most vital part of any aircraft are its powerplants – and making sure they are in perfect condition is no mean feat.

Thousands of commercial aircraft fly passengers and goods to tens of thousands of destinations throughout the world every day. For the commercial aircraft carrying passengers and cargo in very harsh environments, inspection and maintenance for safe operation are crucial (see videos below).

Aviation maintenance is also a lucrative sector. In the United Kingdom the aviation maintenance, repair, overhaul and logistics sector today generates revenues in excess of £15 billion (Dh67.56bn) a year, according to the UK department for business innovation and skills (BIS).

Complexity

For airlines, maintenance, repair and overhaul (MRO) is a costly business. Globally, airlines spent US$62.1bn on MRO, representing around 9 per cent of total operational costs, according to Iata. The MRO industry posted a 2014 net post-tax profit of $19.9bn, compared to $10.6bn in 2013. With a 3.8 per cent increase per annum anticipated, the market size is estimated to reach $90bn in 2024, Iata said.

In 2014, the world fleet count was 24,597 aircraft, with 76 per cent of the fleet manufactured by Boeing or Airbus, the agency added.

In a February survey, the BIS reported that “in terms of future prospects for the industry, several respondents identified what they felt to be a clear opportunity associated with the evolution of the MROL industry. The complexity and sophistication of activities conducted within the industry was felt to be intensifying – and doing so at an increasing rate. This is being driven by the need for increased aircraft serviceability, combined with MROL productivity and efficiency improvements through composite material technologies, data analytics and integrated logistics support.”

In this region, the growth of the ‘big three’ airlines is providing opportunites for MRO companies.

One such is Olympus. The Japanese manufacturer of high-end optics and precision electronics is establishing its Middle East and Africa headquarters to Dubai. The facility will incorporate a state-of-the-art service and training centre for both support and knowledge transfer. From Dubai, the headquarters will cover 72 countries from across southern Africa to the Levant to Turkey to Arabian Gulf countries and elsewhere in the Middle East.

Massive

The move comes as the big three – Emirates, Etihad and Qatar Airways – are poised to expand their fleet by almost 650 new planes. “If you include Turkish Airlines and [others], the order book comes to a massive 1,058 passenger aircraft,” says Maurice Faber, the regional managing director of Olympus. “With the market growing, our local presence here will help support our customers with stronger support on a variety of fronts including faster response times for service and product back-up.”

Periodic inspections of aircraft engines are mandatory by both manufacturers and regulatory authorities. Military aircraft are also subject to strict maintenance programmes.

But, as you are sitting in a passenger plane waiting for take-off, have you ever wondered just how engineers manage to inspect a piece of machinery as complicated and crucial as the engines?

“An aircraft engine is a very complex machine. But manufacturers have provided certain areas within the engine that have access ports to facilitate visual inspection with endoscopes,” says Mr Faber.

Failure

Recently, aircraft have been required to have on-condition maintenance performed, which relies on the capability to detect failures before they happen, so preventive maintenance can be initiated, according to the South Korean industrial endoscope, or borescope, maker Medit.

“Borescopes are becoming instrumental and required to perform these types of inspections,” the company says. “If, during an inspection, maintenance personnel can find evidence that the equipment is approaching the end of its life, then it may be possible to delay the failure, prevent it from happening, or replace the equipment at the earliest convenience, rather than allowing the failure with severe consequences to occur. Modern airplane and helicopter engines are already equipped with endoscope bores.”

Olympus is also a supplier of aviation endoscopes and works closely with industry leaders such as Boeing and Airbus among others. Similar to endoscopy used by doctors to examine patients, these thin, flexible, ultra-high tech tubes are inserted into the access port of an engine. The tube usually has a couple of optical cables, each of which may have up 50,000 optical fibres. The cables carry light and cameras to see inside the engines.

“However, because of the complexity of the engine, there still are various difficulties an inspector may face when attempting to conduct an engine inspection precisely and in a timely manner,” Mr Faber points out.

Laborious

Commercial jets are equipped with turbofan engines, which vary in size from small turbines for regional jets to large turbines for larger, inter-continental airliners. Furthermore, there are many different parts to be inspected within each engine, such as turbine blades, compressor blades and the combustion chamber. It is important when conducting a smooth and accurate inspection, to choose the optimal endoscope and related accessories by engine type and engine part, Olympus says.

“At Olympus, we use a single Iplex videoscope that can cover various demands for aircraft engine inspections by just changing the optical adaptors,” Mr Faber says.

In the past, one aspect of engine inspection involved the laborious procedure of rotating the engine shaft by hand for inspection of the hundreds of blades, which are located at several turbine/compressor stages and mounted on the shaft. It was a two-man operation where one engineer manually rotated the shaft while another inspected the condition of the blades. This work not only required an additional operator for the shaft rotation, but was also a less reliable method.

Today, specific engine turning tools are used, which automatically rotate the shaft with high-pressure compressor/turbine blades at a preferred speed, enabling one inspector too accurately and thoroughly conduct both the shaft rotation and blade inspection operations without the need for a second person.

Images

Recording a large number of blade images for inspection analysis and reporting is necessary, but the images are very similar to each other, meaning attempting to find and sort the data is difficult.

To help in this area, Olympus uses its inspection assist software. After an inspection, the engineer can efficiently analyse the recorded images and immediately create a report, just by selecting desired images with one-click operation, the company says. Its InHelp product is inspection data management and reporting software for Olympus Industrial videoscopes that streamlines all aspects of on-site inspections. It is designed to improve work efficiency by organising stored images and generating detailed inspection reports.

Keeping a jet engine in good condition is a constant operation. “Some basic maintenance occurs on virtually every flight – when the flight crew visually checks the engine condition, lubricant levels and various points designed to highlight an anomaly – such as a dysfunctional low-oil level indicator or any other component indicating something out of specification,” the US aviation journalist Dave Higson tells AvBuyer, an aircraft broker.

“Other powerplant maintenance items arrive largely on an hours or cycles-based schedule, and include the two major events in the life of any turbine engine: the hot-section inspection (HSI); and engine overhaul.”

While some overhauls are proscribed as on-condition events, the HSI generally arrives at a set time period.

“For engines with a proscribed TBO [time between overhaul], HSI events tend to arrive at the mid-point between zero hours and the TBO limit. For engines with an on-condition TBO cycle, however, HSI times are typically set on a firm schedule, whether 1,500 hours, 1,800 hours, 2,000 hours, or more,” Mr Higson says.

Invaluable

“The downtimes vary and costs vary accordingly, but anticipate a low six-figure fee to be a starting point for engines that cost in the high six-figures new. Anticipate seven-figure fees for powerplants with new-production prices well into eight-figure sums. One engine-shop operator uses a rule of thumb that overhauls will cost one-third to one-half of the engine’s cost when new,” he adds.

“Regardless of the renewal costs, the necessity remains to help engines reach their limits, remain cost-effective and, most importantly, reliable and safe.”

So hats off to the backroom boys and girls whose work is seldom seen but whose efforts are invaluable in keeping our planes in the air.

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