Equipment diligence should connect what a qualified reviewer observes with service records, support evidence and actual operating interruptions. Age alone does not establish remaining life, and a stack of repair tickets does not reveal how many scheduled minutes the wash was unavailable.
Define the service path and observation period
Choose one tunnel, independently operating bay or other clearly defined service path. List the start and end of the observation period and the scheduled operating windows within it. Do not combine parallel bays into one denominator merely because they share a site. A fault in one bay may leave another operating. Analyze each path separately before preparing a site-wide interpretation.
Use timestamps with explicit offsets. On a daylight-saving transition, 01:30 at -04:00 and 01:30 at -05:00 are an hour apart even though the clock labels match. The workbook measures elapsed minutes. It merges overlapping scheduled windows so duplicated opening-hour records cannot inflate scheduled time.
Build an asset evidence register
Give each asset an anonymous ID linked to the actual model, serial information and location in the secure file. Record the applicable manual revision, software and controls dependencies, inspection date, open findings, work orders, scoped quotes and accountable technical reviewer. Ask for evidence of parts and service support rather than accepting “still supported” as a complete answer.
| Evidence | Question it helps answer | What remains open |
|---|---|---|
| Inspection and observed operation | What condition was visible on the review date? | Hidden defects, intermittent faults and excluded inspection scope |
| Work orders and downtime logs | What work and interruptions were recorded? | Missing history, changing schedules and unrecorded partial degradation |
| Applicable manual and support confirmation | Which requirements and support arrangements apply? | Whether the operator followed them and what future availability will be |
| Scoped repair or replacement quote | What is included in the proposed work? | Approvals, installation interfaces, closure duration and contingencies |
Sonny’s published surface-conveyor manual is a model-specific example of manufacturer documentation; the reviewed PDF is dated June 7, 2016. It is not a universal maintenance plan or evidence of remaining life for equipment at a subject site. Obtain the correct current instructions for the installed equipment from the manufacturer and qualified service personnel. Example conveyor manual.
Inspection and service can involve hazardous energy. OSHA’s control-of-hazardous-energy material addresses protection during servicing and maintenance. This guide provides no repair or bypass instructions; use trained personnel and the applicable safety procedures. OSHA hazardous-energy resource.
Separate raw events from unique downtime
Record each outage with an event ID, matching asset ID, start, end, source, planned/unplanned/unknown cause and full/partial effect on the chosen path. An open event ends at the observation cutoff and makes the output provisional. Completely blank rows are ignored; incomplete populated rows need correction. Repeated IDs are rejected.
Let S be the union of scheduled operating minutes in the observation period. For full outages, clip every interval to those windows, then merge overlaps to obtain unique full-outage minutes U. Observed availability is 100 × (S − U) ÷ S when S is positive. With no scheduled minutes, availability has no denominator. An empty outage log with incomplete history cannot establish reliability even if the arithmetic shows no recorded outage.
The output also shows raw full-outage minutes, so overlapping tickets are visible. Partial degradation is listed separately and never becomes full downtime by assumption. The cause partition assigns unknown first when it overlaps another cause; otherwise simultaneous planned and unplanned records enter “both.” Planned-only, unplanned-only, both and unknown therefore sum to U without counting the same minute twice.
Worked fictional eight-hour observation
The invented tunnel is scheduled from 09:00 to 17:00: 480 minutes. Planned maintenance from 09:00 to 09:30 contributes 30 minutes. Two faults from 10:00–11:00 and 10:30–11:30 have 120 raw minutes but overlap for 30 minutes, leaving 90 unique unplanned minutes. Total raw full-outage time is 150 minutes; unique full downtime is 120. Observed availability is (480 − 120) ÷ 480 = 75%.
A different operating schedule would change the denominator and possibly the counted outage minutes. An event entirely outside scheduled hours contributes zero to this measure, while still remaining relevant maintenance evidence. Adjacent intervals merge without adding time. The case does not demonstrate a typical availability rate for any wash format.
Turn findings into scoped follow-up
Ask whether repeated faults have a documented common cause, whether work orders close the original finding and whether software, controls or parts dependencies are transferable. Distinguish a recommended repair from a replacement decision. Request a quote identifying equipment, removal, installation, controls integration, civil work, commissioning and service disruption as applicable. Mark excluded work and the party responsible for it.
Carry documented future timing and costs into the replacement reserve tool. Use the incremental project cash comparison when evaluating a change against continued operation. Historical availability alone does not predict future failure, remaining life, replacement timing, lost memberships or investment returns.
Use access and throughput observations for capacity constraints and utility reconciliation for meter evidence. Place open service dependencies in the handoff matrix and the broader due-diligence checklist. Those reviews answer different questions and should retain their own assumptions.
Download the blank evidence register
Download the fictional teaching case v1
Connect operating evidence and the next decision
Chemical inventory and usage · Diligence dependencies and dates. Keep periods and definitions consistent when manually carrying results between tools.
Sources and scope
Official and original sources checked October 17, 2026. These sources support the identified rules and methods; they do not verify a particular business or property.
- Sonny’s — Surface conveyor owner manualModel-specific historical manual example; obtain current instructions for installed equipment.
- OSHA — Control of hazardous energyServicing and maintenance safety context; no DIY service instructions.
Continue your review
Verify the revenue · Normalize earnings · Model the cash flow