🚧 Under construction — VoTechWorks is being built. A free tech program — complimentary, as our commitment to get America working.
voTechWorksGrade 13 · a vocational technology learning center, by urbanicity
newSchoolWorks.com › VoTechWorks › Transportation › Small Engine & Power Equipment › Mowers, Generators, and Chainsaws: Diagnosis, Service, and Repair › Lesson 7
TRN-SMAL74-05 · Lesson 7 · 6 clock hours · practice

Integrated Service Job: Diagnosis, Repair Order, and Quality Inspection Across All Three Equipment Types

Objective. Students will independently diagnose a customer-complaint scenario on each of the three equipment categories, write a complete repair order with parts and labor estimate, perform the repair, and pass a quality inspection.

⚠ Pending professional review

This lesson, its worked examples and its practice questions has not yet been verified by a certified examiner or master technician in the trade or by a certification or approval body. It is a study draft and may contain errors. Do not use it as instructions for work on a job site or on live equipment. Always follow your instructor, your supervising professional, and current official references and regulations.

VoTechWorks program approval and accreditation are still in progress. Credentials are issued only by the certifying bodies named in each program, after their own exams.

Integrated Service Job: Diagnosis, Repair Order, and Quality Inspection

This lesson brings together everything you have practiced across mowers, generators, and chainsaws. You will work as a technician would on a real shop floor: a customer hands you a complaint, you diagnose the fault, write a repair order, perform the repair, and verify your work meets specification before the equipment leaves the bay. Doing all three in one session is intentional — it trains you to shift mental gears quickly, which is exactly what employers expect.

Why the Repair Order Matters

A repair order (RO) is a legal and financial document. It records the customer complaint in the customer's own words, your root-cause diagnosis, every part number and quantity used, and the labor time charged. An incomplete or inaccurate RO creates disputes, eats shop profit, and can expose the business to liability. For the EETC and OEM exams, understanding the RO process also demonstrates professional competency beyond wrench skills.

Every RO you write today must include:

Safety Before You Touch Anything

Lockout/tagout (LOTO) applies at every station. Before diagnosing or repairing any equipment:

1. Disconnect the spark plug wire (and remove the plug on chainsaws and generators requiring cranking clearance) and secure it away from the terminal.

2. On the generator station, verify the unit is de-energized and the output terminals carry no voltage with a meter before touching wiring.

3. On the chainsaw station, engage the chain brake before handling the bar and chain. Wear cut-resistant gloves, chainsaw chaps or equivalent leg protection, eye protection, and hearing protection any time the saw runs.

4. On the mower station, block the blade from rotating before reaching under the deck. Wear safety glasses and gloves.

PPE is not optional and is scored. A LOTO or PPE failure is an automatic lesson fail regardless of your technical score.

Station 1 — Walk-Behind or Riding Mower

A common mower complaint in this exercise is loss of self-propel drive. Your diagnostic path: confirm the complaint by attempting to engage drive, then inspect the drive belt condition and tension, the drive cable adjustment, and the drive wheel engagement components. Trace from the operator control to the final drive point. The root cause is typically a stretched or broken drive belt, a cable out of adjustment, or worn engagement hardware. Document your finding precisely — "drive belt broken" is a root cause; "mower not going" is a symptom, not a root cause.

Station 2 — Portable Generator

Voltage drop under load is a classic generator complaint. Begin with a no-load voltage measurement at the output receptacle using a multimeter set to AC volts — record this figure on the RO. Then apply the resistive load specified on your scenario card and measure again. A significant drop may indicate a governor response issue, a carburetor fuel delivery problem under load, or a faulty automatic voltage regulator (AVR) on inverter-type units. Work through the fuel and governor side first before condemning electrical components. Always confirm output terminals are de-energized and your meter leads are in good condition before measuring.

Station 3 — Chainsaw

Chain oiler failure — chain does not receive bar oil — is a leading cause of bar and chain damage. With the chain brake engaged and the saw off, remove the bar and chain. Inspect the oil pickup port in the guide bar groove, the oil outlet port on the saw body, and the oiler passage. Look for packed sawdust blocking the port. If the passage is clear, the issue may be the oil pump or pump drive worm gear. Confirm the oil tank has fluid before going further — an empty tank is the simplest root cause. Document what you found and what you did.

Parts Look-Up and Estimating

For each station, open the correct OEM parts catalog (print or digital). Navigate by model number from the equipment tag — never guess a part number. Record the exact part number, the list price from the catalog, and the quantity needed. Calculate parts cost as quantity × list price. Calculate labor as (time in hours) × (shop rate from your scenario card). Add parts and labor for the total estimate. Double-check your arithmetic — a transposed digit on an estimate costs the shop real money.

Quality Inspection

After repairs, your peer partner reviews your work using the OEM inspection checklist. They check that fasteners are torqued to spec, guards and covers are reinstalled, fluids are at the correct level, and the complaint is resolved. Then the instructor performs the final inspection, which may include running the equipment and measuring output (blade tip speed, output voltage, oil flow) against OEM specification. Your repair order must match what was actually done — no after-the-fact revisions.

Connecting to Your Credentials

The EETC outdoor power equipment technician exam tests diagnosis process, parts identification, and professional documentation — all of which this lesson exercises directly. OEM certifications from Briggs & Stratton, Stihl, and Honda each require demonstrated competency on their specific platforms, which is why you rotate through equipment from more than one manufacturer. Treating every repair order as a credentialing artifact builds the habits those exams reward.

Key terms9

Repair Order (RO)A shop document that records the customer complaint, technician diagnosis, corrective action taken, all parts used with OEM part numbers and prices, labor time, and total estimated or final charge.
Root CauseThe specific failed or maladjusted component or condition that directly caused the customer's complaint, as distinguished from the symptom the customer described.
Lockout/Tagout (LOTO)A safety procedure that isolates energy sources — spark plug wire disconnected, fuel shutoff closed, electrical terminals de-energized — and prevents accidental re-energization during diagnosis or repair.
OEM Parts CatalogThe manufacturer's official illustrated parts list, organized by model and serial number, that provides the correct part number, description, and list price for every serviceable component.
Automatic Voltage Regulator (AVR)An electronic component in many generators that senses output voltage and adjusts field excitation to keep voltage stable as electrical load changes.
Chain BrakeA safety device on a chainsaw that stops chain movement immediately when activated, either by the operator's wrist contacting the front hand guard or by kickback force; must be engaged before handling the bar and chain during service.
Quality InspectionA structured post-repair check — using an OEM checklist and, where applicable, instrument measurements — that confirms the repair meets specification and the original complaint is resolved before returning equipment to the customer.
Labor EstimateThe portion of a repair order total calculated by multiplying the technician's estimated or flat-rate repair time (in hours or tenths) by the shop's hourly labor rate.
Corrective ActionThe specific repair steps performed to fix the root cause, documented on the repair order in enough detail that another technician could understand what was done.

Worked examples4

1. A generator station scenario card shows: shop rate $85.00/hr, estimated repair time 0.6 hr, one replacement AVR with OEM list price $47.50, and one AVR mounting screw kit at $3.20. Calculate the total repair estimate.
  1. Calculate parts cost: AVR $47.50 + screw kit $3.20 = $50.70
  2. Calculate labor cost: 0.6 hr × $85.00/hr = $51.00
  3. Add parts and labor: $50.70 + $51.00 = $101.70
  4. Write $101.70 as the Total Estimate on the repair order.
Answer: Total repair estimate = $101.70
2. A mower scenario card shows: shop rate $80.00/hr, estimated repair time 0.4 hr, one drive belt with OEM list price $18.95, quantity 1. Calculate the total repair estimate.
  1. Calculate parts cost: 1 × $18.95 = $18.95
  2. Calculate labor cost: 0.4 hr × $80.00/hr = $32.00
  3. Add parts and labor: $18.95 + $32.00 = $50.95
  4. Write $50.95 as the Total Estimate on the repair order.
Answer: Total repair estimate = $50.95
3. A chainsaw station scenario card shows: shop rate $90.00/hr, estimated repair time 0.5 hr, one oil pump assembly at OEM list price $29.00, and one bar-mounting stud kit at $4.50, quantity 1 each. Calculate the total repair estimate.
  1. Calculate parts cost: $29.00 + $4.50 = $33.50
  2. Calculate labor cost: 0.5 hr × $90.00/hr = $45.00
  3. Add parts and labor: $33.50 + $45.00 = $78.50
  4. Write $78.50 as the Total Estimate on the repair order.
Answer: Total repair estimate = $78.50
4. A repair order shows parts totaling $62.30 and a labor time of 0.9 hr at a shop rate of $85.00/hr. What is the total estimate, and what is labor as a percentage of the total (rounded to the nearest whole percent)?
  1. Calculate labor: 0.9 hr × $85.00/hr = $76.50
  2. Calculate total: $62.30 + $76.50 = $138.80
  3. Calculate labor percentage: $76.50 ÷ $138.80 = 0.5512… × 100 ≈ 55%
  4. Record $138.80 as the total estimate; labor is approximately 55% of the total.
Answer: Total estimate = $138.80; labor is approximately 55% of the total.

The math in this lesson1

Learners total $50.70 parts and 0.6 h × $85 labor into a $101.70 repair estimate.
7.EE.3
In class: Three-station timed rotation: each student works through a mower station (e.g., no self-propel drive), a generator station (e.g., voltage drops under load), and a chainsaw station (e.g., chain does not advance oil) — each with a printed customer complaint card — diagnosing the fault, listing root cause and corrective action on a repair order, and performing the repair within the allotted time. · Parts look-up and costing: for each repair, students use the OEM parts catalog (print or digital) to identify the correct part number, look up list price, and calculate a total estimate including labor at a standard shop rate provided on the scenario card, entering all figures on the repair order form. · Peer and instructor quality walk: after repairs, students pair up for a peer review using an OEM inspection checklist, then the instructor performs a final quality inspection, measuring or testing each repair outcome against the specification documented on the repair order.
Materials: One each: walk-behind or riding mower, portable generator, and chainsaw with pre-installed faults (instructor fault kit), OEM service manuals (Briggs, Stihl, Honda), OEM parts catalogs (print or digital access), repair order forms, shop-rate card, inspection checklists, all standard hand and power tools from previous lessons, PPE
Check: Instructor scores each completed repair order on a rubric: correct fault identification (25%), correct parts number and estimate (25%), repair meets OEM specification on final measurement (40%), and LOTO/PPE compliance throughout (10%). Pass = 80% total with no zero in the LOTO/PPE category; a zero in LOTO/PPE is an automatic fail of the entire lesson regardless of other scores.

Practice check8

Answer each question, then check it. Nothing is recorded; this is your own practice.

Professional practices and documentation
1. A technician writes 'mower won't move forward' as the root cause on a repair order. What is wrong with this entry?
Safety — electrical and LOTO
2. Before measuring output voltage on a portable generator, what must the technician verify first?
Safety — LOTO and PPE compliance
3. A student scores 88% overall on the integrated service rubric but receives a zero in the LOTO/PPE category. What is the outcome?
Parts identification and cataloging
4. When looking up a replacement drive belt in an OEM parts catalog, what information is most critical for selecting the correct part?
Chainsaw diagnosis and service
5. A chainsaw oiler is not delivering oil to the bar. After confirming the tank is full and the outlet port on the saw body is clear, what is the next logical component to inspect?
Generator diagnosis and service
6. A generator produces normal no-load voltage but voltage drops significantly when a resistive load is applied. Which two systems should the technician evaluate first?
Safety — LOTO and PPE compliance
7. On the mower station, a student begins by reaching under the deck to inspect the drive area before disconnecting the spark plug wire. Which rubric category is immediately at risk?
Quality inspection and professional practices
8. During the peer quality walk, a student's partner finds that the drive belt was replaced but the belt guard was not reinstalled. According to the quality inspection process, what should happen next?
Record this lesson on my transcript. Sign in with your key and enrollment email to record lessons (enroll free if you have no key). This page stays open to read and practise.