A Word on Global Business Aircraft

Business Aviation and the Boardroom|Dave Higdon| Jan 08,2016|
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Let’s take a very close look at fundamentals.  An aircraft engine endures extreme pressures and temperatures in its daily operations, along with hundreds of hours of use over the course of an average year. During its lifespan, it will undergo scheduled and unscheduled maintenance and inspections, been operated by various pilots, could potentially have powered more than one aircraft and should have accrued detailed notes and records tracking its history and condition that date back to its original build.

Its records ought to be as extensive as the engine itself, meaning there potentially could be some hidden (and unwanted) surprises buried deep within those records waiting to spring on a careless operator.

And yet, among the various Civil Aviation Authorities around the world, engine auditing is not a regulated or certified function within aviation.

To a large extent the responsibility for having the records of a powerplant audited correctly lays with the aircraft owner/operator – so it’s up to that person to appoint somebody with the necessary credentials and experience to ensure all records of the engine are present and correct. Failure to do so during a pre-purchase inspection of an aircraft could result in time-intensive and costly corrections being made further down the line.

For example, we were once tasked with managing the overhaul of an older JT8-219 engine for a VIP aircraft. The technical team delving into the engine’s records discovered they were incomplete, which incurred a substantial amount of additional work (and cost) to authorize the valid EASA release-to-service of the aircraft.

And this wasn’t the first occasion our asset management company—Gamit—has has found incomplete records. On another occasion a privately operated six-year-old aircraft was brought into the shop with the owner seeking its removal from the N-Registry and re-registration on the G-Register. The audit revealed that at a certain point in the aircraft’s life one of the flight crew had mislaid both engine log books, necessitating the lengthy and costly task of having them re-built from scratch in co-ordination with the engine OEM and the various MROs that had performed work on it previously.

Audit Types

There are two specific types of audits that a prospective or current aircraft owner should understand…

Loaner Engine Audits: Usually these are installed when your owned engine is sent away for repair or overhaul. This is usually a short-term item with a quick installation. The records are usually checked back to the engines’ last shop visit, and include all Airworthiness Directives (ADs), Service Bulletins (SBs) and statutes.

If anything looks unusual with this paperwork, however, the auditor will want to dig deeper into the records and go further back in the records.

Pre-Purchase Inspection: These types of audits will track the records going back to the ‘birth’ of the engine – essentially, all of the paperwork is inspected back to engine build. This documentation should all be present and correct.

It’s worth remembering here that engines are not cheap, and they can change aircraft and location many times throughout their life. Engines can also be the cause of aircraft accidents, and if the records are not 100% accurate the Insurance Company could discover those paperwork errors and seek to pin the incident on that fault. If successfully proved, that action would nullify any insurance coverage.

An Involved Process

Typically two main areas play a factor in the initial assessment of an engine’s records irrespective of whether it’s for loaner engines or a pre-purchase audit:

– The Life Limited Parts (LLP) status will show how many serviceable cycles remain on the engine; and

– The Engine Gas Temperature (EGT) recording from the MPA run shows how efficiently the engine is running. This is especially useful if operating in hot temperatures.

Provided that the above two points are acceptable, and assuming that a Borescope inspection is a given before any engine is installed on any type of aircraft regardless of the length of time the powerplant is required to operate on the aircraft, the audit would go into full-swing assessing the engine log books and records to ensure all certificates are in place for work carried out and that all work has been certified correctly.

The AD and SB status can be of particular importance because if certain actions haven’t been taken when they should have been, or are coming up shortly after an owner takes responsibility for the engine, this situation could prove particularly expensive.

Accident and/or incident checks are also essential to an audit, and while mishaps may not have written-off an engine they can be a reason for a low-price for an engine and need to be understood by the prospective operator before taking ownership. In addition, checks should be made that the engine’s total hours and total cycles are correct from the time the engine was installed on the aircraft and when checks subsequently were carried out.

Other essential areas of audit include:

– Repairs Status;

– Borescope Inspections (preferably videos);

– Maintenance Program MPD & Limitations;

– Traceability of Parts (also that the traceability is acceptable to the applicable airworthiness authority of the aircraft that will receive the powerplant);

– Engine Monitoring Documents;

– Reliability Program Documents;

– Corrosion Control Program;

– Shop visit Reports; and

– Maintenance Management System.

As you probably ascertain, engine audits are a complex, involved process. Remembering that the correct conduct of an audit is ultimately the responsibility of the aircraft owner and that audits are not a globally regulated function, who should an owner turn to for assistance?

The following outline provides some basic starting points – although you will need to establish that service providers  have the right experience and certifications specific to your aircraft and engine type.

– Aircraft Management Companies;


– Technical Services Engineers;

– Licenced Aircraft/Engine Engineers;

– Aircraft Quality Manager/Engineers;

– Pilot with an Aircraft Engineering Background.

Only as Good as the Input

Today, there are Maintenance Management Systems used widely by operators to track maintenance that are a good point from which to start your auditing process. Don’t forget, though, that a computer program is only as good as the person who inputs the data.  Mistakes can happen, so it’s also essential to check the dirty finger print records that have the engineer’s signature and stamp.

If all of the above elements check out fine, then you know an engine is in a good state of repair and is acceptable to the airworthiness authority to fit to the aircraft you plan to purchase, or continue to operate while your regular powerplants are at the repair shop.


Dave Higdon writes about aviation from his base in Wichita Kansas. During three decades in aviation journalism Dave has been covering every aspect of civil aviation from sport flying to the airline industry. He spent several years covering the airline industry aviation regulatory and political affairs in Washington D.C. including all the relevant agencies and interest groups. An active instrument rated pilot with more than 5000 flight hours in everything from foot launched wings to business and combat jets he currently writes for Avionics News, Plane & Pilot, Aviation Safety, AvBuyer Magazine and on his podcast Uncontrolled Airspace.