This AIR will provide information on measurements of engine-generated bleed air contaminants that are introduced upstream of other aircraft systems. It describes on-wing measurements during transient and steady state conditions of engine operations. It expands on ARP4418 (Procedure for Sampling and Measurement of Aircraft Propulsion Engine and APU Generated Contaminants in Bleed Air) and AIR6418 (Transient Measurement Method Development for Aircraft Propulsion Engine and Auxiliary Power Unit Generated Contaminants in Bleed Air) for on-ground bleed air test in a test stand This document will focus on sampling systems for on-ground initially. In-flight testing will be addressed at a future time.
Necessary adaptations for collecting samples and making measurements on-wing compared to a test stand are discussed. These include size, power, portability, integration points, source isolation, data acquisition and processing, required tooling to interface with the on-wing bleed system, and routing of the sampling lines.
Rationale: No SAE-E31 document has been written to date to discuss on-wing engine bleed air testing. The E31B charter includes engine bleed air measurement but limits engine bleed air to air that exits a single engine. There are occasions when it may be desired for an engine or APU to be tested on wing, either on-ground, or in-flight, or a combination of both. Some engine conditions cannot be tested on-ground so in-flight testing may be required. In-flight testing will be addressed at a future time.
The locations of sample extraction downstream of the engine bleed port must be carefully considered during test planning. For example, there may be additional contamination sources or altered contaminants or concentrations from heat exchangersor ozone converters. Aircraft systems may range from new systems with odors associated with new systems, to systems that have been in service for many years and may have an accumulation of contaminants in the air supply system if not routinely maintained.
This AIR describes options for sampling engine bleed air as well as tooling to connect bleed air measurement instruments to an electrical supply. This AIR considers effects of maintenance, in-service issues, limitations for on-ground engine power settings, and environmental conditions, but will be bounded in its scope to discuss those portions of the system which are upstream of the mixing manifold and any other aircraft system that may significantly alter the engine bleed air contaminants from the engine of interest.
