Given the wealth the McEvaddy brothers have accumulated during the past 10 to 15 years they have done well in managing to maintain a low profile. Until this week that is.

The two Co Mayo men have grown a small aircraft spare parts business into a global aviation operation that sees them constantly on the move and involved in multi-million pound deals with aircraft companies, national airlines, and the world's largest defence forces.

From a 49 per cent shareholding in Air Gambia, to buying 20 DC-10s from Japan Airlines for $170 million (€162.5 million) to leasing inflight refuelling aircraft to the US Airforce, Ulick (46) and Desmond (45) have come a long way from selling spare parts at Dublin Airport. A significant part of that success has centred on sales to the US military.

According to one source their original business grew very fast and by 1980 the two brothers established Omega Air Ltd, which specialised in Boeing 707s and, according to the company itself was "soon recognised as the largest owner and lessor of both passenger and cargo B707s in the world". Omega Air was incorporated in the Isle of Man and is managed from Sark, in the Channel Islands. Ulick, in particular, is said to have always had a keen interest in aircraft and is an expert on B707s.

"From its founding Omega Air put particular emphasis on the B707 aircraft, having identified a market that had both military and commercial applications," according to the company.

"Building up a considerable fleet of aircraft, Washington-based Omega Air Inc became a major supplier of B707 aircraft to the US military to be used in various tanker, Airborne Warning and Central Systems (AWACS) and Joint Surveillance Target Attack Radar Systems (J STARS) programmes."

The brothers are also involved in a operation since 1996 whereby Omega Air Inc purchased from US company Pratt & Whitney a system for replacing engines on old B707s with new, JT8D-219 engines. The new engines give operators a significant fuel saving, as well as making the aircraft capable of satisfying International Civil Aviation Organisation (ICAO) standards in a number of areas, including noise levels. The latter is the reason the re-engining is sometimes called hush-kitting. Once an aircraft is certified as having met ICAO standards, it may be used in any country.

Omega buys, modifies and leases old B707s, often to customers in Africa, the Middle East and South America. It also leases the aircraft to European charter companies who find themselves short of aircraft at peak periods. The McEvaddy brothers were involved in the development of tourism in Gambia through their 49 per cent ownership of Air Gambia, which began flying between Gambian capital Banjul and London in 1991. The airline uses hush-kitted Omega Air B707s, Air Gambia markings and London-based crews. The flights to London often carry loads which include fish and fruit.

Many of the brothers' customers fly their aircraft between the EU and the Middle East and Africa but a new EU regulation, due to take effect in May 2000, would ban Omega's re-engined aircraft. Mr Ulick McEvaddy, in an affidavit, told the High Court earlier this month that if the EU imposes the ban it will cause Omega to have to devalue its fleet by 30 per cent and write off a $36 million (£26.8 million) investment.

"The proposed EU ban on re-engined aircraft violates EU member states' international obligations and it is this that Omega Air is preparing to challenge in the European Courts," according to the company. "The proposed rule treats domestic and foreign operators differently in violation of the Conventions on non-discrimination principal and it violates EU member states' bilateral air agreement with the US."

Leave was granted in the High Court in London in July for Omega to challenge the introduction of the EU regulation in England and Wales. Omega is seeking a judicial review of the regulation in England and Wales as a means of persuading the High Court to refer the issue to the European courts. Earlier this month the brothers won a temporary injunction against the introduction of the regulation in this jurisdiction, pending a legal challenge it intends taking against the measure.

The $170 million deal with Japan Air in 1997 was unusual for Omega in that it involved DC-10s rather than B707s, the preferred aircraft of the McEvaddys. The DC-10s were bought by a consortium led by Omega Air and sales director Mr Desmond McEvaddy said at the time: "We will offer them for sale or lease and configure the aircraft as the customer wishes."

The company was also to look at the possibility of equipping the aircraft with its in-flight refuelling kit for use by air forces on a lease-by-the-hour basis. Omega is involved with four partners in a Texas-based consortium called Team Inflight Refuelling (IFR), which has carried out flight tests on an in-flight refuelling system, mainly for use on B707s.

One of the partners, Tracor, a large US corporation which sold 78 per cent of its products and services to the US Department of Defence in 1996, converts aircraft to the system in a $6 million operation carried out at a plant in Mojave, California. The converted aircraft can still be used for freight and passenger carrying.

The conflict over the EU noise regulation is seen by the McEvaddys as another EU/US trade issue with the EU and more specifically Germany, France and Britain involved in introducing measures which are to the benefit of European aircraft manufacturers and work against US manufacturers. The issue will be fought out in the EU courts and therefore, they are understood to feel, the current controversy about the Tanaiste, Ms Harney, and the Minister for Finance, Mr McCreevy, staying in an Omega villa near Nice, France, has no substance.

The controversy centres on the view that by staying as guests at the villa the Ministers could be seen to be compromised. The second issue, the attempt by the brothers to build a terminal on land they own adjacent to Dublin Airport, will also be decided in Europe, the brothers argue. A case is being taken to Europe claiming that Aer Rianta's domination of Irish airports is contrary to EU monopoly law. The plan for the privately-owned £50 million terminal has already been rejected by An Bord Pleanala.

However, the brothers have also said that they have been involved in lobbying the Government on both issues and that they employ a firm of lobbyists in Europe to canvass on their behalf.

The two men are said to be typical successful entrepreneurs, driven, quick to make decisions, and tough. "They are very close. When you are talking to just one of them you still think you're talking to two," said an acquaintance. Originally from a farm near Swinford, Co Mayo, the brothers are said to be particularly close to their mother, a National School teacher who reared them after their father died when they were still at a young age. The brothers went to Garbally College, the boarding school in Ballinasloe, Co Galway, rather than the local school.

Ulick went to military college as a equatation cadet and subsequently served as a captain in the supply and transport division. According to a source close to the brothers, Ulick at one stage worked on the army intelligence desk, though army sources say he was not in military intelligence.

He has a strong interest in military strategy and in particular aviation strategy. He is also a member of the London-based Royal United Services Institute, a institution founded by the Duke of Wellington in 1831. According to its publicity the institute is a "professional and independent authority dedicated to the study, analysis and debate of issues affecting defence and international security." It maintains "essential links between the armed forces and those who make decisions under economic and political disciplines".

Desmond went to university and later qualified as a barrister.

The Omega Air business is very successful. "Its huge stuff. You're talking mega bucks," said an acquaintance. "The Dublin Airport project is not such a huge deal for them in the scheme of things."

The brothers have become very wealthy and enjoy their wealth. Desmond bought a house on Shrewsbury Road, Ballsbridge, for £1.55 million in 1996. Within a month of Desmond buying this house Ulick bought Auburn House, on 24 acres, in Malahide, Co Dublin, for £1.47 million. The house is said to be the finest in the Malahide area. They own a private jet which can carry up to 12 passengers, and a private helicopter. A source tells of meeting the brothers in London and being offered a lift home. One brother was flying home in the jet and the other in the helicopter. They both hold helicopter and aircraft pilot licences.

The executive jet was used to fly the late Mother Teresa from Dublin to Belfast during her visit to Ireland, and the helicopter was used to take her to Knock. Mr John Bruton was given use of it recently to travel from Co Cork, where he was holidaying, to the memorial service in Omagh, Co Tyrone, for the victims of the bombing. The brothers have hosted numerous fund-raising events for Fine Gael and Ulick is said to be a strong supporter of Mr Jim Mitchell. When Mr Michael Lowry was Minister for Transport, consideration was given to appointing Ulick to the Irish Civil Aviation Authority.

The villa in Nice is owned by the company and used for company hospitality, but the two brothers have first call on it at all times. Both were known figures on the Dublin social scene up to a few years ago, Desmond more than Ulick.

"When they throw a party, they throw a party. I've been in Ulick's home and it's beautifully appointed, done with great taste. There's no sign of being nouveau riche, even though I suppose that's probably the fact of it."

The brothers both spend a lot of time in Texas and Washington D.C. The business is run from wherever they are rather than from any office or behind any desk, with most decisions being conveyed over the phone. Ulick makes sure he is free for the Horse Show at the RDS every year, where he is a senior steward.

The McEvaddys have a minority shareholding in FM 104, the Dublin radio station. They are also involved in the Malahide Marina project. Their company, Malahide Marina Village Ltd, was approved for a £1.5 million government grant in July 1995. The grant was approved by a committee made up of representatives from the Department of Tourism, Bord Failte, and the tourism industry.