NASA Technical Reports Server (NTRS) 20090015393: Lunar Module Environmental Control System Design Considerations and Failure Modes. Part 2

1.4 MB·English

by  NASA Technical Reports Server (NTRS)

Lunar Module Environmental Control System
Desiign Consiidderatiions & Faiillure Moddes
Part II
Prerequisite
TThhe LLunar MModdulle ((LLMM)) EEnviironmenttall CConttroll SSysttem
(cid:137)
(ECS) Design Considerations and Failure Modes Lesson,
Part I is a pprereqquisite to this lesson.
Objectives
Describe the Lunar Module (LM) Environmental Control
(cid:137)
SSysttem ((EECCSS)) subbsysttem ttesttiing andd reddesiign.
SSuummmmaarriizzee tthhee LLuunnaarr MMoodduullee ((LLMM)) EEnnvviirroonnmmeennttaall CCoonnttrrooll
(cid:137)(cid:137)
System (ECS) in-flight failures.
Subsystem Redesign Considerations -- OSCPS
TThhe OOxygen SSupplly andd CCabbiin PPressuriizattiion SSecttiion
(cid:137)
provided source O2 and cabin pressure.
Subsystem Redesign Considerations -- OSCPS
TThhe CCabbiin RRepress andd EEmergency OOxygen VVallve hhadd
(cid:137)
some problems during feasibility testing, showing the valve
seat to be suscepptible to ppermanent seatingg.
Subsystem Redesign Considerations -- OSCPS
FFiirstt, tthhey chhangedd tthhe vallve seall matteriiall ffrom VViitton BB tto
(cid:137)
Viton VB90.
Subsystem Redesign Considerations -- OSCPS
DDuriing accepttance ttesttiing, tthhe new seatts were seen tto
(cid:137)
crack. The shape of the seat and seal were changed.
Subsystem Redesign Considerations -- OSCPS
TThhe new ddesiign ffaiilledd viibbrattiion-ttemperatture ttesttiing. TThhe
(cid:137)
seat was again changed to provide better centering and
resist lateral movement.
Subsystem Redesign Considerations -- OSCPS
(cid:137)(cid:137) NNomiinall operattiion off tthhe vallve was accompaniiedd bby a very lloudd ““bbang”” ffrom
the high-pressure gas expanding to produce a shock wave.
(cid:138) valve was not actually being damaged
(cid:138) ddeecciissiioonn wwaass mmaaddee nnoott ttoo cchhaannggee tthhee ddeessiiggnn aaggaaiinn
Cabin Repressurization and
Emergency Oxygen Valve
Subsystem Redesign Considerations -- OSCPS
(cid:137) The Oxygen Demand Regulators provided suit loop pressure regulation.
(cid:138) original design sensitive to vibration
(cid:138) various aneroids and mass-balancing techniques reduced the leakage to acceptable
lleevveellss