• Power offtake
• Requirements
• Rolls Royce
• System Engineering
• Turbofan

The MsC thesis describes part of the R-R internal report that I have written during my
Internship at Rolls Royce plc, working in the Trent 1000 Function System Engineering
team. This engine features a completely new layout of the Power Offtake System: in the
Trent 1000 the power is extracted from the IP shaft instead of the HP shaft, as on other
large turbofans. The Trent 1000 powers the Boeing 787 family.
The progressive increase of power extracted from the engine for the More Electric
Aircraft request has raised the issue of the competitive position of 2-shaft vs. 3-shaft
engines and within 3-shaft architecture the effects of using a different shaft to drive the
accessory gearbox.
The aim of this paper is to define which are the key parameters and features of an IP P/O
system, how they are influenced, what are the systems and stakeholders involved and,
qualitatively, how they are influenced. This is done in order to explain and better
understand the decisions made during the design and development of the Trent 1000
( http://www.rolls-royce.com/civil/products/largeaircraft/trent_1000/ ), why certain solutions
have been selected and other rejected, which areas of P/O design require particular
attention and what are the lessons learnt.

The first part of the document is aimed at better understanding the theory and the rationale
behind the IP P/O system and its influences on the engine. In order to do this different
topics are discussed, starting from Load requirements, Idle setting, Engine weight,
Fuel burn, Starting performance, Thermodynamic and Mechanical aspects,
Secondary air system features and Noise. A functional model of the system has been
produced using Artisan Studio which is a tool based on SysML language
The second part is aimed at reviewing the design procedure using the System Thinking
approach, i.e. considering the P/O system not just as the sum of its components but as a
system with different properties, functions and effects. The review of the design process
starts from the Definition of Requirements, proceeds with the Stakeholders Analysis
(only most affected are considered in detail) and ends with a review of the system on the
actual engine (Trent 1000 Pack B): relation between requirements, functions and
implementation, review of ERMS and Lessons Learnt databases and FMECA report.