Removal of an Opposed Type Aircraft Engine

The previous general information related to the removal, buildup, inspection, preservation, storage, and installation of engines is in most instances applicable to horizontally opposed aircraft engines. Finally, the number of accessories, together with fewer engine controls, electrical and hydraulic lines and connections, and the increased ease of accessibility to all parts of the engine generally preclude extensive use of QECA on opposed engines.

The manufacturer’s instructions should always be used as a guide in engine removal or installation. The following is a typical engine removal and installation procedure for a horizontally opposed engine:

1. Remove the propeller.

2. Release the cowl fasteners holding the top cowling, and remove the top cowlings.

3. Remove the screws at the rear of the top and bottom cowling assembly; remove the cowling and store out of the way. [Figure 1]

Removal of an Opposed Type Aircraft Engine
Figure 1. Cowling removed and stored out of the way

4. Disconnect the mechanical fuel pump inlet line.

5. Disconnect the battery leads, then the generator and starter leads.

6. If installed, remove the cylinder head temperature thermocouple.

7. Disconnect the oil pressure and manifold pressure lines.

8. Disconnect the oil return line.

9. Remove the bonding strap from the rear of the engine.

10. Disconnect the governor control cable from the governor.

11. Disconnect the tachometer cable from the rear of the engine.

12. Disconnect engine oil cooler hoses.

13. Disconnect the engine oil temperature lead.

14. Disconnect the engine breather line.

15. Remove the four carburetor mounting nuts and allow the carburetor and carburetor air box to hang by means of the attached engine controls.

16. Attach a hoist to the engine-lifting eye and relieve the tension on the mounts. [Figure 2]

Removal of an Opposed Type Aircraft Engine
Figure 2. Relieve tension on engine mounts

17. Disconnect magneto P-leads.

Remove the cotter pin, nuts, washer, and front rubber mount from each bolt and remove the sleeve. Slide bolts out of attaching points. Swing engine free, being careful not to damage any attached parts, and remove rear rubber mounts, as shown in Figure 3.

Removal of an Opposed Type Aircraft Engine
Figure 3. Engine clear of mount