Chapter 37 Page Date: 8. December 1999 37 Page 1
Table of Contents 37-00-00 GENERAL...3 Description...3 System Surview...4 System Components...5 Troubleshooting...6 37-10-00 DISTRIBUTION...8 37-10-01 Pump...8 Removal (LH / RH Side)...8 Installation...8 37-10-02 System Inlet Filter...8 Filter Element Replacement...8 37-10-03 Regulator Valve...9 Removal (LH Side)...9 Installation (LH Side)...10 Removal (RH Side)...10 Installation (RH Side)...10 Filter Element Replacement...11 37-10-04 Check Valve Manifold...11 Removal...11 Installation...12 Page 2 37 Page Date: 5. July 2002
37-00-00 GENERAL Description The vacuum and pneumatic system (refer to Figure 30-01) is installed to provide a source of vacuum for the vacuum instruments and the de-icing boots, and also air pressure for the latter. The system consists of two engine driven dry air pumps, vacuum and pressure regulating valves, vacuum and pressure manifolds with internal check valves, the suction gage and the gyro instruments. Furthermore the components of the de-icing system, such as control and distribution valves, timer, and pressure switches are incorporated in the system. Each air pump operates continuously when the engine is running and pulls a vacuum on the common vacuum manifold. The maximum amount of vacuum pulled on the manifold by each air pump is controlled to a preset level by each vacuum regulating valve. Should either of the pumps fail, a check valve is provided in each end of the manifold to isolate the inoperative pump from the system. The exhaust air side of each attitude gyro is connected to the vacuum manifold thus providing a smooth steady vacuum for the gyros. The vacuum pressure being applied to the gyros is constantly present on the suction gage. This gage also provides failure indicators for the left and right air pumps. These indicators are small red buttons located in the lower portion of the suction gage which are spring-loaded to the extended (failed) position. When normal vacuum is applied in the manifold, the failure buttons are pulled flush with the gage face. Should insufficient vacuum occur on either side, the respective red button will extend. No corrective action is required by the pilot, as the system will automatically isolate the failed vacuum source, allowing normal operation on the remaining operative vacuum pump. The inlet air side of the attitude gyros are connected to a common vacuum air filter located between the LH and RH keelbeams, which cleans the air before allowing it to enter the gyro. (With SN 03 through 14, the air inlet filter is installed in the fuselage portion of the wing). At the same time the air pumps pull a vacuum on the common vacuum manifold they provide air pressure to the common pressure manifold. However, the pressure side is active only if de-ice system is ON. The maximum amount of air pressure in the system is controlled to a preset level by a pressure regulating valve. Should either of the pumps fail, a check valve is provided in each end of the manifold to isolate the inoperative pump from the system. Controlled by the timer, the distributing valve of the de-icing system, which is connected to the vacuum and the pressure manifold, takes either vacuum or pressure as required for the respective cycles of the activated de-icing system (refer also to Paragraph 7.25 in Pilot's Operating Handbook). In case air pressure is not necessary, the de-ice control valve exhausts the air to relieve the pressure system. Page Date: 5. 11. July August 20022000 37 Page 3
1H5-29 5000B-52 4000B-22 Hoses not designated specified to MIL-H-5593-6 Figure 37-01 System Surview Legend line from vacuum system inlet filter to gyro installation line from gyro installation to vacuum manifold line from vac. manifold to LH vac. regulating valve / vac. pump line from vac. manifold to RH vac. regulating valve / vac. pump LH / RH pressure lines from vac. pump to pressure manifold / de-ice system line from vac. manifold to de-ice system LH vacuum line from vac. manifold to dual source differential vac. gage RH vacuum line from vac. manifold to dual source differential vac. gage line from gyro inlet manifold to dual source differential vac. gage line from attitude indicator to dual source differential vac. gage Page 4 37 Page Date: 5. July 2002
System Components Refer to Figure 37-01. Item Manufacturer Part-Nr. Qty. Engine Driven Pump optional: Airborne Aero Accessories A/M 442CW-6 CH 442CW-6 2 2 Attitude Indicator King KI 256 060-0017-01 1 Pneumatic Attitude Gyro (Copilot) optional: RC-Allen Sigma-Tek RCA22-11F 5000B-52 1 1 Pneumatic Directional Gyro (Copilot) optional: RC-Allen Sigma-Tek RCA11A-17BF 4000B-22 1 1 Regulator Valve Airborne 2H3-6 2 Check Valve Manifold Airborne 1H5-29 1 Dual Source Differential Gage Airborne 1G5-4 1 System Inlet Filter Extra 75551.00 1 System Inlet Filter Element Airborne D9-18-1 1 Triple Bulkhead Fitting Line Extra 25227.80 1 Triple Bulkhead Fitting Line -6 Extra 25227.04 1 Bulkhead Fitting Gyro Suction Line Extra 75554.10 1 Gyro Inlet Manifold Extra 75552.10 1 Gyro Outlet Manifold Extra 75553.10 1 hose fittings protected by spring clamps VW 60184-xx Hose Elastic Clamp -4 VW 60184-15 -6 VW 60184-19 -8 VW 60184-23 -10 VW 60184-27 Page Date: 5. July 2002 37 Page 5
Troubleshooting Complaint Possible Cause Remedy Correct indication on vacuum gauge, bull s eye pops up No indication on vacuum gauge, no bull s eye popped up No indication on vacuum gauge, both bull s eyes popped up gauge indication low indication high pump defective plumbing defective plumbing defective gauge defective regulator maladjusted Both vacuum pumps defective gauge defective regulator maladjusted plumbing defective system filter dirty regulator maladjusted Identify and replace defective vacuum pump Check and replace defective plumbing Check and replace defective plumbing Replace vacuum gauge Identify and readjust vacuum regulator Replace both vacuum pumps Replace vacuum gauge Identify and readjust vacuum regulator Check and replace defective plumbing Replace vacuum system filter Identify and readjust vacuum regulator Erratic vacuum indication Drive pad seal leakage Replace seal Premature vacuum pump failure Excessive gyro precession Incorrect pump model Pump overload due to airflow restriction or system contamination Restricted airflow due to leaking or kinked lines or clogged filter Install correct clockwise (CW) rotating pump Replace defective and contaminated components before replacing pump Check and replace defective plumbing, replace vacuum filter Gyro failure Replace gyro, see chapter 34 Gauge indication follows engine rpm Frequent regulator adjustment Foreign matter in regulator seat Regulator defective Kinks in lines, deteriorated hoses, leaking hose connections Remove contamination and reset regulator Replace defective regulator Check and replace defective plumbing, reset regulator Page 6 37 Page Date: 5. July 2002
NOTE Use Airborne 343 Test Kit to troubleshoot vacuum and pressure system, and to readjust regulating valves. Page Date: 5. 11. July August 20022000 37 Page 7
37-10-00 DISTRIBUTION 37-10-01 Pump Refer to Airborne Service Letter No. 58, latest edition. Removal (LH / RH Side) Turn battery switch OFF and pull OFF circuit breaker BOOTS (left side panel) before beginning work. When working on vacuum system, take care not to contaminate vacuum hoses. Install blind plugs on hose ends. Even small residues of dirt may damage air pumps. 1 Remove upper cowling 2 Disconnect vacuum hose from vacuum regulator valve 3 Disconnect pressure hose to de-ice control valve VW spring clamp at vacuum pump VW spring clamp at vacuum pump 4 Pull off plastic semi-circular cooling shroud from top of vacuum pump 5 Unscrew 4 nuts from pump flange installation wrench required 6 Remove vacuum pump Installation Install in reverse sequence of removal Caution Install new gasket between pump and flange 37-10-02 System Inlet Filter Filter Element Replacement 1 Filter assembly Extra EA-75551.00 with filter element Airborne D9-18-1 (to be used with ADI KI-256 installation or aircraft approved for known icing operation): The filter assembly is located in the bottom fuselage area, between the LH and RH keelbeams. Page 8 37 Page Date: 5. July 2002
2 Filter assembly Airborne with filter element Airborne D9-18-1: The filter assembly is located in RH wing leading edge. To gain access, remove the wing center fairing. Removal 1 Remove 10/32 UNF nut securing filter assembly to fuselage resp. wing section 2 Pull threaded rod out of filter assembly 3 Remove internal distance bushing 4 Remove filter assembly from fuselage resp. wing section 5 Replace filter element Installation Install in reverse sequence of removal NOTE Use new polystop nuts 37-10-03 Regulator Valve Removal (LH Side) Turn battery switch OFF and pull OFF circuit breaker BOOTS (left side panel) before beginning work. When working on vacuum system, take care not to contaminate vacuum hoses. Install blind plugs on hose ends. Even small residues of dirt may damage air pumps. 1 Remove upper cowling 2 Disconnect vacuum hose from regulator valve at firewall to vacuum pump VW spring clamp at regulator valve 3 Cut off vacuum hose from vacuum check valve manifold; remove VW spring clamp and hose end at regulator valve 4 Remove tightening nut of regulator valve from bracket at firewall Use 1 ¼ inches crowfoot wrench 5 Remove regulator valve to outward direction of engine compartment Page Date: 5. July 2002 37 Page 9
Installation (LH Side) 1 Tighten regulator valve with nut to bracket at firewall 2 Install new vacuum hose to vacuum check valve manifold Use 1 ¼ inches crowfoot wrench s 3 Install vacuum hose to vacuum pump 4 Install upper cowling Removal (RH Side) Turn battery switch OFF and pull OFF circuit breaker BOOTS (left side panel) before beginning work. When working on vacuum system, take care not to contaminate vacuum hoses. Install blind plugs on hose ends. Even small residues of dirt may damage air pumps. 1 Remove upper cowling 2 Disconnect vacuum hose from regulator valve at firewall to vacuum pump 3 Disconnect vacuum hose from gyro installation VW spring clamp at regulator valve VW spring clamp at vacuum check valve manifold 4 Cut off vacuum hose from vacuum check valve manifold; remove VW spring clamps and hose ends 5 Remove tightening nut of regulator valve from bracket at firewall Use 1 ¼ inches crowfoot wrench 6 Remove regulator valve to outward direction of engine compartment Installation (RH Side) 1 Tighten regulator valve with nut to bracket at firewall 2 Install new vacuum hose to vacuum check valve manifold Use 1 ¼ inches crowfoot wrench s 3 Install vacuum hose from gyro installation 4 Install vacuum hose to vacuum pump Page 10 37 Page Date: 5. July 2002
5 Install upper cowling Filter Element Replacement On vacuum regulator valve an Airborne B3-5-1 foam filter element is installed. The filter element can be replaced without removing the regulator valve. Draw the filter element from the regulator body. Install the same way. Refer to Airborne Service Letter No. 59, latest edition. 37-10-04 Check Valve Manifold Refer to Airborne Service Letter No. 39, latest edition. Removal Turn battery switch OFF and pull OFF circuit breaker BOOTS (left side panel) before beginning work. When working on vacuum system, take care not to contaminate vacuum hoses. Install blind plugs on hose ends. Even small residues of dirt may damage air pumps. 1 Remove upper cowling 2 Disconnect pressure hose from LH vacuum pump to de-ice control valve at firewall 3 Disconnect vacuum hose from LH regulator valve to vacuum pump VW spring clamp at de-ice control valve VW spring clamp at regulator valve 4 Cut off pressure hose from LH de-ice control valve to pressure check valve manifold; remove VW spring clamps and hose ends 5 Cut off vacuum hose from vacuum check valve manifold to LH regulator valve; remove VW spring clamps and hose ends 6 Disconnect pressure hose from RH vacuum pump to de-ice control valve 7 Disconnect vacuum hose from RH regulator valve to vacuum pump VW spring clamp at de-ice control valve VW spring clamp at regulator valve 8 Cut off pressure hose from RH de-ice control valve to pressure check valve manifold; remove VW spring clamps and hose ends Page Date: 5. July 2002 37 Page 11
9 Cut off vacuum hose from vacuum check valve manifold to RH regulator valve; remove VW spring clamps and hose ends 10 Disconnect vacuum hose from LH dual source differential vacuum gage to vacuum check valve manifold 11 Disconnect vacuum hose from gyro installation to vacuum check valve manifold 12 Disconnect vacuum hose from RH dual source differential vacuum gage to vacuum check valve manifold 13 Disconnect vacuum hose from de-ice system to vacuum check valve manifold 14 Disconnect pressure hose from pressure check valve manifold to de-ice system VW spring clamp VW spring clamp VW spring clamp VW spring clamp VW spring clamp 15 Cut electrical wiring to de-ice control valves on both sides of 2 splices 16 Remove vacuum installation holder bracket from firewall 17 Remove vacuum check valve manifold from holder bracket 4 bolts M6 2 bolts and nuts M6 Installation 1 Install vacuum check valve manifold to vacuum installation holder bracket 2 Install holder bracket to firewall 3 Install pressure hose from pressure check valve manifold to de-ice system 4 Install vacuum hose from de-ice system to vacuum check valve manifold 5 Install vacuum hose from RH dual source differential vacuum gage to vacuum check valve manifold 6 Install vacuum hose from gyro installation to vacuum check valve manifold Page 12 37 Page Date: 5. July 2002
7 Install vacuum hose from LH dual source differential vacuum gage to vacuum check valve manifold 8 Install new vacuum hose from vacuum check valve manifold to LH regulator valve 9 Install new pressure hose from LH de-ice control valve to pressure check valve manifold 10 Install vacuum hose from LH regulator valve to vacuum pump 11 Install pressure hose from LH vacuum pump to de-ice control valve at firewall 12 Install new vacuum hose from vacuum check valve manifold to RH regulator valve 13 Install new pressure hose from RH de-ice control valve to pressure check valve manifold 14 Install vacuum hose from RH regulator valve to vacuum pump 15 Install pressure hose from RH vacuum pump to de-ice control valve s s s s 16 Re-establish splices at electrical wiring to de-ice control valves 17 Install upper cowling Page Date: 5. July 2002 37 Page 13