Inspecting a Reciprocating Engine Exhaust System for the A&P Practical

October 25, 2026 · Primary sources checked October 25, 2026

Inspect a reciprocating engine exhaust system for cracks, dents, missing parts and evidence of leakage, including its joints, supports and concealed internal components. Never use galvanized or zinc-plated tools on it, and never mark its parts with a lead pencil.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151

This Airframe and Powerplant (A&P) oral and practical (O&P) guide organizes an A&P practical exhaust system inspection around the assigned aircraft’s current instructions, not universal damage limits.

What does this O&P inspection evaluate?

AM.III.L.K1 — Reciprocating engine exhaust system theory, components, operation, and inspection. AM.III.L.S1 — Identify the type of exhaust system on a particular aircraft. AM.III.L.S3 — Inspect a reciprocating engine exhaust system. AM.III.L.S4 — Inspect exhaust system internal baffles or diffusers. AM.III.L.S5 — Inspect exhaust heat exchanger. AM.III.L.S7 — Perform a pressure leak check of a reciprocating engine exhaust system.

FAA-S-ACS-1, printed 58, PDF 63

AM.III.L.R1 — Maintenance and inspection of exhaust system components. AM.III.L.R3 — Operation of reciprocating engines with exhaust systems leaks. AM.III.L.R4 — Exhaust system failures. AM.III.L.R5 — Ground operation of aircraft engines.

FAA-S-ACS-1, printed 58, PDF 63

The Federal Aviation Administration (FAA) Airman Certification Standards (ACS) elements listed above are the ones this guide covers; they do not guarantee this particular assignment. A practical project combines one skill element with two practical questions and permits available, applicable references for both. Passing requires a successful first-attempt skill demonstration and successful answers to both related questions. The required performance standard is in the downloaded test.

Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)c) · Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)f) · Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929, printed 16, PDF 16, 5-5-11-7C3)g)

Start with aircraft data and the hazards

Advisory Circular (AC) 43.13-1B describes its inspection-and-repair methods for nonpressurized civil-aircraft areas only when manufacturer repair or maintenance instructions are absent. The circular also says each exhaust repair must meet the manufacturer’s specifications. Identify the installed system, its inspection access, applicable limits and required checks before handling it; stop the rehearsal where that data is missing.

AC 43.13-1B, Change 1, printed unnumbered cover page, PDF 1, Purpose, paragraph 1 · AC 43.13-1B, Change 1, printed 8-27, PDF 406, 8-50

For identifying the installed system (AM.III.L.S1), the Powerplant handbook (FAA-H-8083-32B) names two general types of reciprocating-engine exhaust systems: the short stack (open) system and the collector system.

FAA-H-8083-32B, Powerplant, printed 3-21, PDF 149

Any exhaust-system failure should be regarded as a severe hazard. Depending on its location and type, failure can cause carbon monoxide poisoning, partial or complete engine-power loss, or an aircraft fire. The ACS safety appendix says the evaluator ensures the applicant observes safety precautions, such as wearing safety glasses, hearing protection, and any other required personal protective equipment (PPE). If an action would jeopardize safety, the evaluator will ask the applicant to simulate that portion. Any disregard for safety is not tolerated and will result in a failure.

FAA-H-8083-32B, Powerplant, printed 3-22, PDF 150 · FAA-S-ACS-1, printed A-3, PDF 67

For this rehearsal, treat engine starting, hot components and pressurization as separate controlled operations: use the assigned maintenance and ground-run instructions, required protection and the evaluator’s directions rather than improvising a live demonstration.

Expose the system and preserve leakage evidence

Before cleaning, remove cowling as required and inspect adjacent cowling and nacelle areas for soot showing possible leaks. Check that cowling, engine-control cables or other components are not chafing the exhaust system. AC 43.13-1B notes that the exhaust system often operates at red-hot temperatures of 1,000 °F or more. For that reason, protect nearby ignition leads, hoses, fuel lines and flexible air ducts from radiant and convective heat with heat shields or adequate clearance. Remove or loosen the shields, heater muffs, shrouds and heat blankets required to inspect the complete system.

AC 43.13-1B, Change 1, printed 8-26, PDF 405, 8-49a · AC 43.13-1B, Change 1, printed 8-26, PDF 405, 8-49b

Keep the marking and cleaning cautions intact

The handbook says lead, zinc or galvanized marks are absorbed when the exhaust metal is heated, changing its molecular structure. That change softens the marked area, causing cracks and eventual failure. AC 43.13-1B additionally says never to use lead pencils, carbon-based pencils or similar tools to mark exhaust parts. The circular explains that carbon deposited by those tools will cause cracks from heat concentration and carbonization of the metal. If marking is necessary, the circular specifies chalk, Prussian blue, India ink, or a carbon-free grease pencil.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151 · AC 43.13-1B, Change 1, printed 8-26, PDF 405, 8-49 CAUTION

Ceramic-coated exhaust stacks should be cleaned only by degreasing, never with sandblast or alkali cleaners. Do not turn that limited list of marking media into approval for an arbitrary shop marker, or transfer a cleaning method from a plain finish to a ceramic coating.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151

Inspect external surfaces, joints and internal parts

Give close attention to welds, clamps, supports, support lugs, bracing, slip joints, stack flanges, gaskets and flexible couplings. Examine bends, weld-adjacent areas, dents and low spots for thinning and pitting caused by internal erosion or accumulated moisture. The handbook describes an ice pick or similar pointed instrument as useful for probing suspected areas. Use the assigned inspection method and limits; this mention is not permission to puncture a serviceable component or invent a rejection depth.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151

Disassemble as necessary to inspect internal baffles or diffusers. Internal failures of baffles or diffusers can cause partial or complete engine-power loss by restricting exhaust flow. If pieces of internal baffling break loose and partially or totally block the exhaust flow, engine failure can occur. An exhaust outlet guard does not remove the need for thorough internal inspection or replacement of defective mufflers.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151 · FAA-H-8083-32B, Powerplant, printed 3-24, PDF 152 · AC 43.13-1B, Change 1, printed 8-26, PDF 405, 8-48

Inspect the heat exchanger and account for carbon monoxide

A failure in the heat-exchanger surface, usually the muffler’s outer wall, allows exhaust gases to escape directly into the cabin-heat system. Failed heat-transfer-pin spot welds can also permit exhaust leakage. Besides the carbon monoxide hazard, failed heat-exchanger surfaces can admit exhaust to the engine induction system and cause overheating and power loss. Exhaust manifold and stack failures are usually fatigue failures at welded or clamped points. Although these failures are primarily fire hazards, they also present carbon monoxide problems. Exhaust gases may enter the cabin through defective or inadequate seals at firewall openings, wing-strut fittings, doors and wing-root openings.

FAA-H-8083-32B, Powerplant, printed 3-24, PDF 152 · AC 43.13-1B, Change 1, printed 8-23, PDF 402, 8-46a

Use the assigned leak check and finish the installation

A component that is inaccessible for a thorough visual inspection, or hidden by nonremovable parts, should be removed and checked for possible leaks. The handbook describes plugging component openings, applying suitable internal pressure of approximately 2 pounds per square inch (psi), and submerging the component in water so leakage produces bubbles. AC 43.13-1B says to dry the component thoroughly before reinstallation. Use the assigned component procedure and its pressure limitations; the handbook’s approximate 2 psi description is not a substitute for that data.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151 · AC 43.13-1B, Change 1, printed 8-26, PDF 405, 8-49d

After complete installation and securing all engine cowling, the handbook calls for operation to normal exhaust temperature, shutdown, cowling removal and inspection of clamped and exhaust-port connections. Flat gray or sooty black streaks indicate an exhaust leak, which is usually the result of poor alignment of two mated exhaust-system members. For a leaking connection, loosen clamps and reposition the units for a gas-tight fit before tightening within the specified torque. If the specified torque does not eliminate looseness, replace bolts and nuts because they have probably stretched; safety all nuts after specified tightening. Perform the described run only through the applicable ground-operation and hot-component controls; do not handle the system as if shutdown immediately makes it safe to touch.

FAA-H-8083-32B, Powerplant, printed 3-23, PDF 151

Recognize turbocharger, augmentor and repair boundaries

Turbocharged exhaust operates at greatly increased pressure and temperature, so extra care and maintenance precautions should be taken. During high-altitude operation, the turbocharged exhaust-system pressure is maintained at or near sea-level values; because of that pressure differential, any leak allows exhaust gases to escape with torch-like intensity that can severely damage adjacent structures. Wastegate coke deposits can cause sticking closed and overboost, while deposits in the turbo itself cause gradual power loss and a low pre-takeoff manifold-pressure reading. Clean, repair, overhaul and adjust these components and controls in accordance with the applicable manufacturer’s instructions.

FAA-H-8083-32B, Powerplant, printed 3-24, PDF 152

Inspect augmentor tubes for alignment, security, condition and cracks even when they do not contain heat-exchanger surfaces. Augmentor cracks can create fire or carbon monoxide hazards by admitting exhaust into nacelle, wing or cabin areas.

FAA-H-8083-32B, Powerplant, printed 3-24, PDF 152

The handbook generally recommends new or reconditioned exhaust components rather than repair. When welded repairs are necessary, retain original contours and do not warp or otherwise affect alignment. Internally protruding repairs or sloppy weld beads are unacceptable because they cause local hot spots and may restrict exhaust flow. Always use proper hardware and clamps; do not substitute steel or low-temperature self-locking nuts for the manufacturer’s brass or special high-temperature locknuts. Never reuse old gaskets or old star lock washers; after disassembly use new gaskets of the same type supplied by the manufacturer.

FAA-H-8083-32B, Powerplant, printed 3-24, PDF 152 · AC 43.13-1B, Change 1, printed 8-27, PDF 406, 8-50

Common rehearsal mistakes to avoid

Our check points: do not clean away evidence before examining adjacent areas, stop at the first visible crack without completing assigned coverage, treat an outer shell as proof that internal baffles are sound, or approve a part from a handbook example instead of applicable limits. Record the component, location, observed condition, method and applicable reference used for the decision; explain any condition that prevents completion rather than inventing an acceptance limit.

For examiner fees and planning, read the DME exam cost guide.

Related guides

• Engine Exhaust and Reverser Oral Exam Questions and Answers
• Engine Inspection Oral Exam Questions and Answers
• A&P Practical Projects: What the DME Evaluates on the O&P

Sources

Primary sources checked October 25, 2026.

• AC 43.13-1B, Change 1
• FAA-S-ACS-1
• Order 8900.1, Vol. 5, Ch. 5, Sec. 11, CHG 929
• FAA-H-8083-32B, Powerplant

About this guide: drafted with AI from the FAA sources listed on this page and checked claim by claim against them. Not reviewed by an A&P mechanic or DME. How we make our guides