FAA Releases Revision to General, Airframe and Powerplant Handbooks in Advance of Testing Transition

UPDATE: Following last Thursday’s release of the revised airframe and powerplant handbooks, the FAA released a revision to the general handbook on July 28. A summary of changes to the general handbook have been added to the story below, which was originally published on July 27.

The week of July 24, the FAA published long-awaited revisions to the General, Airframe, and Powerplant Aviation Maintenance Technician Handbooks. The handbook revisions are in response to the transition to the Mechanic Airman Certification Standard (ACS) as the testing standard on Aug. 1, 2023. The ACS became the part 147 curriculum standard last September, when the new part 147 went into effect.
 
The new release should not require major adjustment to align curriculum training materials. In its most recent Airman Testing Community Advisory (dated July 2023), the agency characterized the forthcoming revision as “minor,” an understatement at best. The changes are mostly editorial in nature and do not align handbook content with the ACS—that necessary and prudent adjustment is expected in the next “major” revision, scheduled for publication in June 2024 (general) and 2026 (airframe and powerplant).
 
Part 147 programs are required by regulation to align curriculum with the Mechanic ACS. Schools should continue to teach all included subject matter—without the benefit of handbook guidance—for any subject area not covered in FAA guidance. That said, given that all test questions must tie back to an ACS code and at least one regulatory reference listed in Chapter 8 of the ACS Companion Guide, if an element is not covered in a regulatory reference (most often the general, airframe, or powerplant handbook or AC 43.13-1), ATEC does not expect the subject matter to be tested.
 
Many thanks to our good friends at ASA who have conducted and shared a list of substantive changes to the handbooks. (For programs using ASA publications, expect the 2024 Test Guides to incorporate the ACS and this latest handbook revision. The publisher’s new versions will begin shipping in October).
 
Both handbook revisions combine two separate volumes into one and make global changes (in many but not all instances) to remove gender-specific pronouns and remove and replace the terms “cockpit” with “flight deck,” “disk” with “disc,” “tow-in” with “toe-in,” “tow-out” with “toe-out,” “fuel/air” with “air-fuel,” “counterweight” with “flyweight,” and “airplane” with “aircraft.”
 
A high-level summary of the substantive changes to each handbook are as follows:

Aviation Maintenance Technician Handbook – General (8083-30B)

1. Pages 7-61 to 7-63: Added new subsection entitled HI-LOK™ Fastening System.
2. Page 7-63: Revised HI-TIGUE™ Fastening System subsection to read: “The HI-TIGUE™ fastener offers all the benefits of the HI-LOK™ fastening system along with a unique radius contour on the thread lead-in, or a raised bead design that enhances the fatigue performance of the structure making it ideal for situations that require a controlled interference fit. The HI-TIGUE™ fastener assembly consists of a pin and collar. These pin rivets have a radius at the transition area. During installation in an interference fit hole, the radius area will “cold-work” the hole. These fastening systems can be easily confused, and visual reference should not be used for identification. Use part numbers to identify these fasteners.”
3. Page 7-64: Added new subsection entitled HI-LITE™ Fastening System.
4. Page 8-22: Changed the term “Alodine®” to “Bonderite®” in the Alodizing subsection.
5. Pages 11-23 to 11-25: Revised Figure 11-39 addressing vernier scale readings and accompanying text setting forth example 2 (last sentence on page 11-23 through the end of that paragraph on the following page).
6. Page 12-14: Added new sentence to the end of first paragraph under Electron Flow: “The Federal Aviation Administration (FAA) officially defines current flow using electron theory (negative to positive).”
7. Page 12-29: Revised last sentence under Current Limiter subsection to read “The schematic symbol for the current limiter shows two triangles pointing to each other with a line on both sides of the triangles.”
8. Page 12-30: Revised Figure 12-67 (added current limiter symbol).
9. Page 14-31: Deleted subsection entitled “Decoding Human Factors,” previously located under the Other Resources subsection (three remaining subsections are unchanged).

Aviation Maintenance Technician Handbook – Airframe (8083-31B)

1. Pages 1-8 and 1-9: Added “Reinforced shell” as the third class of monocoque fuselage types and added a new subsection entitled “Reinforced Shell Type” (on page 1-9) with the following subtext: “The reinforced shell has the skin reinforced by a complete framework of structural members.”
2. Page 1-38: Added the following new paragraph under the Access & Inspection Panels subheading: Quick access to the accessories and other equipment carried in the fuselage is provided for by numerous access doors, inspection plates, landing wheel wells, and other openings. Servicing diagrams showing the arrangement of equipment and location of access doors are supplied by the manufacturer in the aircraft maintenance manual.
3. Pages 3-15 to 3-17: Added three new subsections under the “Seams” heading to address “Fabric Seams,” “Sewn Seams,” and “Doped Seams.” Also added a new Figure 3-21 Fabric Seams and renumbered subsequent Figures in Chapter 3.
4. Page 4-32: Modified the first paragraph under the “Rivet Strength” subheading setting parameters for replacing rivets when a replacement rivet has lower strength properties or when the rivet hole becomes enlarged, deformed, or otherwise damaged.
5. Page 5-20: Added the following paragraph directly under the Soldering subheading: Soldering is a method of thermally joining metal parts with a molten nonferrous alloy that melts at a temperature below 800 °F. The molten alloy is pulled up between close-fitting parts by capillary action. When the alloy cools and hardens, it forms a strong, leak-proof connection.
6. Pages 11-65 to 11-67: Added new subsections to the Emergency Locator Transmitter (ELT) subheading (which starts on page 11-63) entitled Testing Considerations for 406 MHz ELTs (starting on page 11-65) and 406 MHz Testing (on page 11-67).
7. Page 11-70: Added a new section entitled Aircraft Communication Addressing & Reporting System (ACARS).
8. Page 13-23: Added new leading paragraphs under Landing Gear Position Indicators section.
9. Page 13-44: Added new figure 13-44 and renumbered subsequent figures in Ch 13.
10. Page 14-2: Added new text to the Fuel Storage System section (last four sentences at the end of the first paragraph) to address fuel dump systems.

 
Aviation Maintenance Technician Handbook – Powerplant (8083-32B)

1. Page 1-8: Added two sentences to the end of the Crankshaft Balance subsection to direct a runout check of a crankshaft as the first step to engine overhaul.
2. Page 1-38: Added last paragraph to Compressor Section (right before Compressor Types subheading) to address vortex dissipaters.
3. Page 1-40: Added the following new paragraph under Axial-Flow Compressor subheading (starting with "The axial flow compressor...).
4. Pages 1-43 and 1-46: Added “Reverse-flow type” as a fourth basic type of combustion chambers (added as number 4 in the second numeric list on page 1-43) and added a description of a reverse-flow combustor (page 1-46, paragraph directly before Turbine Section subheading).
5. Page 2-8: Added new first sentence under the Carburetor Types section header to make clear there are two types of aircraft carburetors (float-type and pressure-type).
6. Page 2-41: Revised system categories for engine driven fuel pumps (numeric list under Main Fuel Pumps (Engine Driven) subheader) to “Nonconstant displacement” and “Nonpositivie displacement” (previously Constant displacement and Nonconstant displacement, respectively) and inserted new text in the subsequent paragraph (starting with “A nonpositive-displacement pump produces…” and ending with “…pump pressure relief valve opens.”).
7. Page 3-2: Added new sentence to Basic Carburetor Induction System subsection regarding application of carburetor heat to operating engine (third sentence in last paragraph).
8. Page 3-3: Added new sentence to Induction System Icing subsection (fourth sentence in next-to-last paragraph) regarding application of carburetor heat or induction system anti-icing when icing is not present.
9. Page 3-4: Inserted new text to the Induction System Inspection & Maintenance subsection (at end of second paragraph) regarding importance of filter system cleaning.
10. Pages 3-4 and 3-5: Added new subsection entitled Extinguishing Engine Fires. 
11. Page 3-12: Added new sentence to the A Typical Turbosupercharger System subsection (at end of second paragraph) regarding impact of not closing turbocharger waste gate.
12. Page 3-14: Added new sentence to the Turbocharger Controllers & System Descriptions subsection (in the first paragraph) regarding impact of destabilization of waste gate or controller.
13. Page 3-17: Added new sentence to the Turbine Engine Inlet Systems section (at end of second paragraph) regarding inlet ducts design function.
14. Page 3-19: Added new sentence to Bellmouth Compressor Inlets subsection (after first sentence in first paragraph) regarding most common use of bellmouth inlet duct.
15. Page 4-3: Inserted new text in Primary Electrical Circuit subsection (after second paragraph) setting forth the three basic events required to fire a spark plug when its piston is in the prescribed position.
16. Pages 4-12 through 4-14: Added new section entitled Types of DC Generators, added new figures 4-21 through 4-25, and renumbered subsequent figures in Chapter 4.
17. Pages 4-16 to 4-17: Added new subsection entitled Engine Indicating & Crew Alerting System (EICAS).
18. Page 6-31: Added new paragraph to Turbine Engine Oil System Maintenance section (last paragraph on page) regarding checking and servicing aircraft engine oil.
19. Page 6-32: Added new sentence to Reciprocating Engine Cooling Systems subsection (last sentence on page) regarding blast tube cooling functions.
20. Page 7-16: Added new sentence to the Constant-Speed Feathering Propeller subsection (at the end of the first paragraph) regarding propeller position prior to engine shutdown.
21. Page 7-20: Added 6 new paragraphs after first paragraph of Autofeathering System section.
22. Page 7-21: Added new text to Aluminum Propeller Inspection section (third and fourth sentences) regarding prohibition of repairs to shanks and manufacturer’s limits.
23. Page 8-1: Changed “Sudden Stoppage” subheading to “Engine Sudden Stoppage or Propeller Strike” and replaced first two sentences with: “Engine sudden stoppage causes a very rapid and complete engine stoppage. Propeller strikes can cause either reduction in speed or a complete engine stoppage.”
24. Page 8-7: Inserted new text to Disconnection of Engine Controls subsection (end of second paragraph) regarding control rod end test hole.
25. Page 9-7: Inserted new paragraph to Fire Extinguishing Agents subsection (second paragraph) regarding carbon dioxide as an extinguishing agent.
26. Page 10-2: Inserted new paragraph to General Overhaul Procedures section (last paragraph in that section, right before subheading Receiving Inspection) regarding Safety Bulletins.
27. Page 10-24: Inserted new text to Cylinder Head Temperature Indicator subsection (at end of second paragraph) regarding further interpretation of cylinder head temperature gauge (figure 10-39).