MODUK DERD 2153 PDF

INTRODUCTION

INTRODUCTION This Specification states the requirements of the Procurement Executive, Ministry of Defense for assessing the sensitivity of gas turbine engine and ramjet engine fuel and control systems to abrasion and/or obstruction if solids occur in the fuel. It is a Service requirement that engine fuel and control systems shall have the capability for operating with contaminated fuel when the normal standards of fuel cleanliness cannot be maintained. The tests prescribed are to demonstrate an arbitrary acceptable capability of an engine fuel and control system within permissible margins of engine performance deterioration.

No departure from the requirements of this Specification will be permitted unless sanctioned by DG/Ehg(PE).

References to specifications (other than individual engine specifications) , manuals and documents referred to herein shall be deemed to be the latest issues or editions and any amendments thereto; references to an individual engine specification shall be deemed to be the issue of the specification stated in the relevant contract.

The measurements and other data obtained, together with relevant information from other development testing, w i l l be used to assess individually or collectively the following aspects, of fuel and control system performance:

a. abrasion and obstruction. the need for further design improvements to mitigate the effects of abrasion and obstruction 

b. the provision of basic information from which-servicing and maintenance instructions can be written stating when the protection given by filters must be renewed by replacement or cleaning, and

c. to declare an ultimate point beyond which the fuel and control system perfomance cannot be predicted if filter protection is abandoned.

The initial 4 x 6 hour cyclic testing described in para 5, Rig Tests for Systems - Gas Turbine Engines, is a formal demonstration of the acceptable capability when filter protection is available, although there may be a curtailment of normal life expectancy under persistent contamination conditions in service.

Supplementary testing as described in para 6, Supplementary Rig Tests for Systems - Gas Turbine Engines, without filter protection (or with reduced filter protection) may or may not be called for, and is intended to confirm whether there is a further reserve capability available in an emergency. described in para 6' are deemed to be necessary then the requirements of para 5.7 will not be carried out until after the supplementary rig tests have been completed, (see para 6.3).