High-Cost of a Hangar System Discharge

NFPA 409, Standard on Aircraft Hangars clearly outlines fire protection system requirements, components, and design criteria.  These system designs are based on several factors including, hangar class, hangar size, fueled or unfueled storage, and the presence of hazardous operations.  These criteria are laid out in order to provide the greatest level of coverage and fire protection, with the least chance of a false activation or accidental discharge.

As we discuss these false activations, we are talking about an instance when the sprinkler and/or foam system activate, agent is expelled from the sprinkler heads, but there is no fire event in progress. The cost of an accidental discharge can be astronomical and have far-reaching consequences.  These costs are related to:

1. Damage to aircraft
2. Cost to recharge/refill foam supply
3. Cost to retain and remove foam contaminant effluent
4. Manpower costs
5. Loss of future business

Foam and water discharge can cause significant damage to an aircraft engine and avionics, especially when the nacelle (casing around the engine) is open for servicing.  An almost equal amount of damage can be caused to sensitive electrical components if the system discharges into an open cockpit.  If a discharge happens under these conditions, each part must be inspected, cleaned, and treated.  A study by the Navy estimated the repair cost to be half that of a full replacement.

Based on where you look, the cost of foam (AFFF) concentrate starts at around $1,000 for 55 gallons. Hangars requiring foam systems would require thousands of gallons of this concentrate.  A 1,000 gallon tank recharge/refill could cost nearly $20,000. 

The foam discharged is required by environmental protection guidelines to be captured, retained, and properly disposed of.  If a system is activated, the discharge should flow into the trench drainage system, it would then flow to a holding area.  All the discharged liquid will have to be removed by tanker trucks, this would also have to include the wash down water from cleaning the foam residue left in the trench and on the hangar surfaces.  Low estimates for this are around $1 per gallon transported.

The clean up and additional aircraft maintenance and repair all require manpower.  This is unplanned work that an employee must be paid to fulfill (often at overtime pay rates).

Perhaps, the biggest cost, could be the economic factor, a loss of future business.  An accidental discharge could cause current and future customers to lack faith in the organization, stop current programs, or prohibit future purchases.  The loss of one large contract could put the company out of business.

The most common reason for a false activation or accidental discharge is improper maintenance and lack of following proper testing procedures.  NFPA 409 provides clear guidance on the inspection, testing, and maintenance of these systems.

The book and resource guide, NFPA 409 - Resource Guide, is available now.  This guide is intended to be used in conjunction with NFPA 409, Standard on Aircraft Hangars.  

The Resource Guide provides clarification on the code requirements, outlines hangar classifications, describes the construction process, and defines the fire protection system installation and maintenance procedures. Purchasing this guide provides access to a complete training program for you and your staff, an audio presentation, and a collection of checklists to ensure that compliance is maintained.  

Answer this in the comments section:
Have you ever experienced a false system discharge?  What was the root cause?

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