Monday, September 12, 2016

Fire Protection for Engine Test Facilities

Long before an aircraft takes flight, each component undergoes a rigorous barrage of tests. Aircraft engines must be tested to ensure that they meet the design goals, can withstand set tolerances, and are in accordance with FAA airworthiness standards.  These engine tests take place at a designated engine test facility within an engine test stand or cell (the enclosed space where a test engine is installed) .


Engine Test Cell - MDS

NFPA 423, Standard for Construction and Protection of Aircraft Engine Test Facilities outlines the fire protection features that must be in place to adequately protect these expensive assets.  An engine test facility is defined as any "integrated system that includes a building(s), a structure(s), and services used to test aircraft engines within a test cell or on a test stand."  

NFPA 423 provides four components for adequate fire protection of engine test facilities.

1. Portable Fire Extinguishers

Fire extinguishers are required to be provided throughout the facility and located outside of the engine test area.  The primary hazard to be accounted for is the fuel and other flammable liquids that are integral to the engine testing and operation process. Extinguisher selection in the engine test areas should be appropriate for a Class B, Extra Hazard location.  Proper selection of these fire extinguishers is outlined in NFPA 10, chapter 5.

2. Fire Alarm and Communications Systems

A fire alarm system is required and must be installed in accordance with section 9.6 and section 40.3.4 of NFPA 101, and NFPA 72, National Fire Alarm and Signaling Code.

*Authors Note: it is unclear from NFPA 423:6.1.6 whether the intent is to require fire alarm systems at all engine test facilities or in only those test facilities that meet the occupant load factors of NFPA 101:40.3.4.1.  This question has been submitted to the NFPA.  When an answer is received, it will be posted in the comments section below this post. How would you interpret this section?

3. Fixed Fire Protection Systems

Each engine test cell area must have its own fixed fire protection system.  NFPA 423 allows the use of carbon dioxide, gaseous agents, dry chemical, foam, or water spray systems.  However, due to the sensitive nature of the engine components, it is advisable to utilize a clean agent system (i.e., Halotron).  These systems do not leave any residue, or create any additional mess when activated, and will prevent additional down-time.

Clean agent systems are required to be designed, installed, and maintained in accordance with NFPA 2001, Standard on Clean Agent Fire Extinguishing SystemsEach system must have a 100% agent reserve supply available for immediate manual discharge.  A system activation must also close all fuel supply valves to the engine and activate the fire alarm.

4. Personnel Training

All personnel that will be involved with engine testing operations or working within the facility are required to receive regular fire safety training. All personnel are to be trained on the proper operation of all types of fire extinguishers throughout the facility. 

Select personnel, on each operational shift, are be trained in the operation and activation of the fixed fire protection systems.  These personnel should have a clear understanding of the features of the system, activation procedures, and the area it protects.  Key personnel should be designated the responsibility for the inspection and maintenance of the fixed fire suppression system.


Click the picture for actual engine test video