Wednesday, December 18, 2013

“You say repairable, and I say reparable. You say rotable, and I say recoverable … So let’s call the thing exchangeable!” *

“Engineman Fireman Recruit Megan Cotrell conducts maintenance on an engine in one of the main spaces aboard the amphibious transport dock ship USS New Orleans (LPD 18).”[i] (Photo courtesy U.S. Navy)
There’s a term for everything in logistics. The problem is, the specific meaning of a term is often nuanced and depends on where you work or where you “grew up” as a logistician. Since every logistics organization has its own dialect, we take a closer look at several terms for spare parts, especially those parts managed by readiness-based sparing (RBS).
A closer look at terminology

Table 1 includes some of the more common terms and definitions for spare parts.  Use this table as a convenient point of reference...or translation; investigate the citations further to better understand the specific intent behind each usage.

Table 1 General Definitions

General term
Reference definition
Repair part
“Part required to return a vehicle to operational condition, necessary to perform its intended purpose. This does not include maintenance supplies; such as, wiping rags, antifreeze, radiator flush and stop-leak, solvents, grease, etc.”[ii]
Spare part
“An individual part, sub-assembly or assembly supplied for the maintenance or repair of systems or equipment.”[iii]
Service parts
“Those modules, components, and elements that are planned to be used without modification to replace an original part.”[iv]

Table 2 provides some additional specificity and definitions for spare parts based upon the item’s ultimate usage.

Table 2 Specific Definitions

The item is consumed or loses its identity in use.
Specific term
Reference definition
Consumable item
“An item of supply (except explosive ordnance and major end items of equipment) that is normally expended or used up beyond recovery in the use for which it is designed or intended.”[v]
Expendable item
“Item [that] is consumed in use or [that] loses its original identity during periods of use by incorporation into, or attachment upon, another assembly.”[vi]
Shop supplies
“Expendable items consumed in operation and maintenance (waste, oils, solvents, tape, packing, flux, welding rod).”[vii]
The item is not consumed and retains its identity while in use.
Specific term
Reference definition
Capital spare
“[C]apital spares are not consumed or used to destruction on the basis that they can be repaired and so become ‘rotable items’.”[viii]
Exchangeable item
“Recoverable components, such as pumps, electric motors, carburetors, and fuel controls.”[ix]
Recoverable item
“A spare part [that] normally is not expended in use and [that] can be reused after recovery and repair.”[x]
Repairable item
·       “An item that can be reconditioned or economically repaired for reuse when it becomes unserviceable.”[xi]
·       “A component, module, assembly, subassembly or equipment determined by the inventory manager to be economically repairable when it becomes unserviceable.”[xii]
Reparable item
“An item of supply subject to economical repair, and for which the repair (at either depot or field level) of unserviceable assets is considered in satisfying computed requirements at any inventory level.”[xiii]
Rotable item
“[R]otable spare parts are materials and supplies … that are acquired for installation on a unit of property, removable from that unit of property, generally repaired or improved, and either reinstalled on the same or other property or stored for later installation.”[xiv]
Rotable pool
“Supply's inventory of repairable items is commonly referred to as the ‘rotable pool’ or just the ‘pool’."[xv]
Note: Two definitions include qualifying statements. 
The USAF definition for reparable includes this addendum: “This term suggests the logistics status rather than the condition of an item.”[xvi]
The IRS definition for a rotable is further explained as: “flight equipment rotable spare parts and assemblies are tangible property for which depreciation is allowable while expendable flight equipment spare parts are materials and supplies.”[xvii]

In short, two broadly applicable definitions will work well in most logistics conversations regarding spare parts:[xviii]

1.     Consumable items are typically low-cost items that are consumed in use. Consumable items also lose their identity when installed on higher assemblies (you do not distinguish the part from the whole). It is usually physically or economically infeasible to repair failed consumable items—better to replace them. Common consumables include nuts, bolts, paint, wire, solder, memory chips, and brackets.

2.     Reparable items are high-cost items that are not consumed in use. It is often mechanically and economically feasible to repair these items. Examples of reparables (which retain their identity when in use) include items such as radios, radar units, engine components, or landing gear.

Readiness-based sparing methodologies are commonly applied to the management of inventories of reparable items and select (typically higher-cost) consumable items.

If you are still confused, don’t fret, you are not alone. The very etymologies of reparable and repairable differ.  Reparable comes from the Latin reparabilis meaning “able to be restored or regained,” while repair (and repairable) comes from the Latin reparare meaning “to restore, put back in order.”[xix]  Obviously, the need for repairing and maintaining equipment goes back a long, long time!

“Staff Sgt. Christopher Matthews, an aerospace propulsion systems craftsman with the 52nd Component Maintenance Squadron, inspects an F-16 Fighting Falcon exhaust nozzle March 16, 2010, at Spangdahlem Air Base, Germany.”[xx] (Photo courtesy of the U.S. Air Force)

* With a sincere thanks and acknowledgment to George and Ira Gershwin for their timeless music and corruptible lyrics. Also, a special thanks to Maggie Wise for her review and very helpful suggestions regarding this posting.

[i] U.S. Navy Photograph by Mass Communication Specialist 2nd Class Dominique Pineiro/Released, USS New Orleans (LPD 18), downloaded from on 6 Mar 2013. 
[ii] Department of the Air Force.  The USAF Supply Manual.  AFM 23-110, Vol I, Pt. 1, Chap 1, “General and Administrative,” Atch 1A-1 (Definitions and Supporting Information), Washington: HQ USAF, 31 Mar 2005. (p. 1-102)
[iii] McCann, Colonel John A., USAF (Ret.), ed. Compendium of Authenticated Systems and Logistics Terms, Definitions, and Acronyms.  AU-AFIT-LS-3-71.  School of Systems and Logistics, AFIT, Wright-Patterson AFB OH, 1981. (p. 637)
[v] Office of the Deputy Under Secretary of Defense for Logistics and Materiel Readiness (DUSD[L&MR]), DoD Supply Chain Materiel Management Regulation, DoD 4140.1-R, 23 May 2003. (p. 192)
[vi] Department of the Air Force, 2005. (p. 1-73)
[vii] McCann (p. 627)
[viii] United Kingdom Ministry of Defence. Defence Logistics Support Chain Manual.  JSP 886, Vol 2, Part 6 “Financial Accounting for Inventory,” Ver. 1-5, 5 February 2013, p. 8.  Downloaded from on 22 Apr 2013.
[ix] McCann (p. 273)
[x] McCann (p. 571)
[xi] Department of Defense.  Department of Defense Dictionary of Military and Associated Terms, Joint Publication 1-02, 8 November 2010 (As Amended Through 15 October 2011). (p. 288)
[xii] Department of the Navy.  Supply Appendices.  NAVSUP P-485 Volume II - Supply Appendices, Revision 4, Glossary of Supply Abbreviations, Acronyms and Terms, Part B: Terms, Naval Supply Systems Command, NAVSUP HQ, 18 May 2009. (p. G-86)
[xiii] Department of the Army.  Logistics Provisioning of U.S. Army Equipment.  Army Regulation 700–18.  Washington, DC, Headquarters, 20 September 2009. (Page 31)  Downloaded from on 6 March 2012.
[xiv] U.S. Government, Internal Revenue Service.  Internal Revenue Bulletin: 2012-14, T.D. 9564 Guidance Regarding Deduction and Capitalization of Expenditures Related to Tangible Property, April 2, 2012.  Downloaded from  on 14 Dec 2013.
[xv] Wirwille, James W. and William T. Ainsworth.  Analysis of a Proposal to Consolidate Aircraft Intermediate Maintenance Capabilities.  MS Thesis, Naval Postgraduate School, Monterey CA, December 1991 (AD-A246187). (p. 22)
[xvi] Department of the Air Force, 2005. (p. 1-102)
[xvii] U. S. Government.  Federal Register. Guidance Regarding Deduction and Capitalization of Expenditures Related to Tangible Property - A Rule by the Internal Revenue Service on 09/19/2013.  Downloaded from on 14 Dec 2013.
[xviii] Pankonin, Captain George C. and Captain David K. Peterson. A Spares Stockage Algorithm for Low-Density Equipment. MS thesis, AFIT/GLM/33-82.  School of Systems and Logistics, Air Force Institute of Technology (AU), Wright-Patterson AFB OH, September 1982 (ADA123709). (pgs. 8-9).
[xix] Harper, Douglas. Online Etymology Dictionary.  Accessed 14 December 2013.
[xx] U.S. Air Force Photograph by Airman 1st Class Nick Wilson, downloaded from on 15 December 2013.