ENGINE NOSE COWL - INSPECTION/CHECK
1.  Engine Nose Cowl Inspection
A.  General
(1)  
On the engine nose cowls without the porous metal acoustical panels; for the approved damage limits and repairs refer to the SRM 54-30-1.

(2)  
On the engine nose cowls with the porous metal acoustical panels; for the approved damage limits and repairs refer to the SRM 54-30-1, and/or the Rohr Repair Manual 54-30-01 (P/N 173-1200, 173-1203).

506 
Oct 20/91  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  71-11-31 Page 601/602 

ENGINE NOSE COWL - CLEANING/PAINTING
1.  Engine Nose Cowl Cleaning
A.  General
(1)  
On acoustic nose cowls, intensive mass airflow of the engine tends to cause contaminant buildup on the nose cowl acoustical liners and can cause a degradation in acoustical performance. Cleaning of the nose cowl is accomplished to remove contaminants from the acoustical liners and improve acoustical performance.

(2)  
Nose cowl cleaning is accomplished by spraying water into the engine inlet.

(3)  
To prevent water from entering the engine, the engine inlet must be prepared for cleaning by blocking.

B.  Equipment and Materials
(1)  
Plug, Engine Inlet - Boeing F72783-1, -2, and -3

(2)  
Water tank - approximately 250-U.S. gallon capacity, equipped with pump or a potable water source - 35 to 100 psi discharge pressure, with associated hose and nozzle with flow capacity of approximately 80 to 100 gal/min

(3)  
Solvent - Ethyl Alcohol (Denatured), AMS 3002 (used during freezing conditions)

(4)  
Solvent - Methyl Alcohol, AMS 3004 (used during freezing conditions)

C.  Clean Engine Nose Cowl
(1)  Install engine inlet plug as follows:
(a)  
Insert F72783-1, -2, and -3 plug segments into engine inlet in that order (Fig. 701).

(b)  
Position curved end of each hook assembly around aft edge of the adjacent inlet guide vane. While holding hook T-handle securely, tighten each wingnut finger-tight.

501 
Nov 01/74  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  71-11-31 Page 701 

Engine Nose Cowl Cleaning Figure 701 
Percent Alcohol By Volume  Outside Air Temperatures (OAT)
 3 6 9 14 17 20 22 23  40°F (4.4°C) 38°F (3.3°C) 36°F (2.2°C) 33°F (0.6°C) 31°F (-0.6°C) 28°F (-2.2°C) 26°F (-3.3°C) 25°F (-3.9°C) 
Minimum Required Ethyl Alcohol-Water Mixtures Table 1 
Percent Alcohol By Volume  Outside Air Temperature (OAT)
 5 10 15 20  40°F (4.4°C) 33°F (0.6°C) 27°F (-2.8°C) 22°F (-5.6°C) 
71-11-31Page 702  Minimum Alcohol-Water Mixtures  Figure 702 Minimum Required Methyl Alcohol-Water Mixtures Table 2 BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  501 Nov 01/74 

CAUTION:  EXCESSIVE TIGHTENING OF WINGNUTS WILL DAMAGE ENGINE INLET GUIDE VANES.
(2)  
Cap PT2 probe in nose dome.

(3)  
If nose cowl is to be cleaned during freezing temperature conditions, add sufficient alcohol to the wash water to ensure no ice forms that could cause damage to the engine. See  Fig. 702 for recommended minimum water-alcohol mixtures. However, a mixture of up to 50% alcohol may be used.

CAUTION:  ALKALINE CLEANERS AND ABRASIVES MUST NOT BE USED. DAMAGE TO ACOUSTIC LINER CAN RESULT.

(4)  
Spray clean tap water or water/alcohol mixture on the acoustic liner for approximately 30 seconds. Approximately 40 to 50 gallons of water may be discharged in the 30-second interval.

(5)  
Repeat step (4) as many times as desired to obtain desired cleanliness.

(6)  
Remove cap from PT2 probe.

(7)  
Remove engine inlet plugs F72783 and inspect inlet guide vanes.

501 
Nov 01/74  BOEING PROPRIETARY - Copyright . - Unpublished Work - See title page for details.  71-11-31 Page 703 

ENGINE NOSE DOME - REMOVAL/INSTALLATION
1. General
A.  Engine nose domes are designed to provide proper airflow for optimum engine performance. Therefore, keeping the nose dome aerodynamically smooth is important to the maintenance of optimum engine performance. Before installing, examine outer surface of nose dome for damage. No damage is allowed to any area of aluminum honeycomb core (Ref Rohr Repair Manual 54-30-01).
B.  Because of the difficulty in reworking an engine nose dome to original smoothness, extreme care should be taken when handling the nose dome to avoid denting the exterior surface and to prevent damage to the Pt2 probe assembly.
　
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