SIC 3724 — Aircraft Engines and Engine Parts
Official OSHA SIC Manual Definition
Establishments primarily engaged in manufacturing aircraft engines and engine parts. This industry also includes establishments owned by aircraft engine manufacturers and primarily engaged in research and development on aircraft engines and engine parts whether from enterprise funds or on a contract or fee basis. Also included are establishments engaged in repairing and rebuilding aircraft engines on a factory basis. Establishments primarily engaged in manufacturing guided missile and space vehicle propulsion units and parts are classified in Industry 3764; those manufacturing aircraft intake and exhaust valves and pistons are classified in Industry 3592; and those manufacturing aircraft internal combustion engine filters are classified in Industry 3714. Establishments primarily engaged in the repair of aircraft engines, except on a factory basis, are classified in Transportation, Industry 4581; and research and development on aircraft engines on a contract or fee basis by establishments not owned by aircraft engine manufacturers are classified in Services, Industry 8731.
Description & Classification
SIC code 3724 representing 'Aircraft Engines and Engine Parts' is an industry category in the Standard Industrial Classification (SIC) system under U.S. OSHA and Federal procurement registers.
Modern NAICS Crosswalk
Trace the modern equivalent classifications in the 2022 North American Industry Classification System (NAICS) database:
- NAICS 336412 - Aircraft Engine and Engine Parts Manufacturing (via SIC1987:3724→NAICS1997:336412→2002:336412→2007:336412→2012:336412→2017:336412→2022:336412)
- NAICS 541714 - Research and Development in Biotechnology (except Nanobiotechnology) (via SIC1987:3724→NAICS1997:54171→2002:541710→2007:541711→2012:541711→2017:541714→2022:541714)
- NAICS 541713 - Research and Development in Nanotechnology (via SIC1987:3724→NAICS1997:54171→2002:541710→2007:541711→2012:541711→2017:541713→2022:541713)
- NAICS 541715 - Research and Development in the Physical, Engineering, and Life Sciences (except Nanotechnology and Biotechnology) (via SIC1987:3724→NAICS1997:54171→2002:541710→2007:541712→2012:541712→2017:541715→2022:541715)
Classification Details
| SIC Code | 3724 |
|---|---|
| Industry Title | Aircraft Engines and Engine Parts |
| Division | Division D: Manufacturing |
| Major Group | Major Group 37: Transportation Equipment |
| JSON Endpoint | View as JSON · API → |
| Source / Verified | US Census 1987 SIC Concordance / 2026-08-08 |
SIC vs NAICS Compliance & Common Mismatches
Legacy SIC code 3724 classifies commercial operations based on primary end-product or service output under the 1987 federal framework. In contrast, modern 2022 NAICS codes group establishments based on production process inputs.
When submitting public disclosures to SEC EDGAR or determining OSHA workplace safety log recordkeeping exemptions (29 CFR Part 1904), rely strictly on the official OSHA 4-digit SIC classification rather than an automated commercial translation.
💡 Expert Guidance: SIC to NAICS Conversion
Common Compliance Mistake: Many contractors and B2B analysts confuse legacy 4-digit SIC codes like 3724 with modern 6-digit NAICS codes. Ensure that you use the correct active 2022 NAICS code (e.g. from the crosswalk below) when submitting representations on SAM.gov, as federal contracting officers only accept modern NAICS codes.
Related Pages & Tools
Further regulatory reference links for legacy SIC code 3724:
- SIC Codes Complete Compliance Guide — Detailed history and active legal applications of the SIC classification framework.
- Why Legacy SIC Codes Persist Guide — How credit systems and the SEC still rely on SIC metadata.
- SIC ↔ NAICS Crosswalk Tool — Trace industrial code conversions dynamically.
- SIC 3724 to NAICS Crosswalk — Bidirectional mapping to modern NAICS codes (Aircraft Engines and Engine Parts).
- SIC Major Group 37 Hub — View other legacy industries in this business division.
Frequently Asked Questions (FAQ)
What industry sector is represented by legacy SIC code 3724? ▾
Legacy SIC code 3724 represents 'Aircraft Engines and Engine Parts', categorized under Division Division D: Manufacturing and Major Group Major Group 37: Transportation Equipment. The Standard Industrial Classification (SIC) system was developed in the late 1930s.
What is the modern 2022 NAICS equivalent for legacy SIC 3724? ▾
Legacy SIC code 3724 maps to the modern 2022 NAICS industry classifications: NAICS 336412 (Aircraft Engine and Engine Parts Manufacturing), NAICS 541714 (Research and Development in Biotechnology (except Nanobiotechnology)), NAICS 541713 (Research and Development in Nanotechnology), NAICS 541715 (Research and Development in the Physical, Engineering, and Life Sciences (except Nanotechnology and Biotechnology)). Mappings are resolved transitively across successive updates to handle splits.
Why do credit agencies and banks still reference legacy SIC code 3724? ▾
Registries like Dun & Bradstreet, insurance underwriters, and private platforms retain SIC code 3724 because their historical financial risk data and scoring models are indexed using the legacy 4-digit SIC framework.
Does the SEC EDGAR system allow searching public filings by SIC 3724? ▾
Yes. The SEC Division of Corporation Finance assigns a primary 4-digit SIC code to public companies. You can search the EDGAR database using SIC code 3724 to group reporting peer firms.
How do OSHA safety recordkeeping rules apply to SIC code 3724? ▾
Under 29 CFR Part 1904 safety regulations, OSHA references legacy SIC codes including 3724 to determine if a physical establishment is required to maintain daily injury logs (Form 300) or is partially exempt.
What is the structural difference between SIC 3724 and NAICS codes? ▾
SIC code 3724 classifies establishments based on their final product output or market destination (what they sell), while modern NAICS codes classify them based on production processes and inputs (how they work).
What are the typical business activities classified under legacy SIC 3724? ▾
Typical business activities classified under legacy SIC 3724 are the operations associated with 'Aircraft Engines and Engine Parts'. Mapped modern NAICS codes can be referenced for specific current examples.
Is legacy SIC code 3724 uniform across all 50 U.S. states? ▾
Yes, the Standard Industrial Classification (SIC) system, including code 3724, was published as a federal standard and remains uniform nationwide. It is still referenced by various state workers' compensation boards and departments of labor.
Sources & References
- U.S. Department of Labor (OSHA): OSHA Standard Industrial Classification (SIC) Manual — Code 3724
- U.S. Census Bureau: 1987 SIC to 2022 NAICS Concordance Tables
- Federal Reserve Board: Industrial Production & Capacity Utilization Classifications
- Internal Revenue Service (IRS): Schedule C Principal Business Activity (PBA) Industry Concordance
- Office of Management and Budget (OMB): Standard Industrial Classification Systems Governance